Calculators you can cite.

Balances complete combustion for a user-entered fuel composition: element totals, stoichiometric oxygen as C + H/4 + S - O/2, and the CO2, H2O, SO2, residual O2 and inert products at either a specified excess air or an excess air inferred from a measured dry O2. It is a stoichiometric screen, not a combustion or emissions determination.

Computes mixture molecular weight, specific gas constant and density from a user-entered gas composition: mole fractions from entered amounts, Mmix as the mole-weighted sum, and rho = P*Mmix/(Z*Ru*T). Entries may be required to sum to unity or normalised from any positive total. Component properties stay user inputs, so it is a gas-basis calculator rather than a property database.

Accounts annual emissions through a serial control train: uncontrolled mass entered directly or as activity times a user-entered emission factor, then each stage removing capture x effectiveness x reduction efficiency of its inlet and passing the remainder on. Control performance stays a user input; it is a mass-balance accounting aid, not a permit calculation.

Applies the dry-basis oxygen reference correction, factor (20.9 - Oref)/(20.9 - Omeas), forward or in reverse. The correction is dimensionless so the concentration unit is unchanged. It is an arithmetic correction, not a determination of which reference oxygen a rule requires.

Converts a gas pollutant between ppmv and mass concentration through the ideal-gas molar density P/(RT) and a user-entered molecular weight, then multiplies by volumetric flow on the same gas basis to give a mass emission rate. It is a unit and basis conversion; it supplies no emission factors.

Converts a stack-gas volumetric flow between wet and dry bases and normalises it to user-entered reference conditions: the dry fraction is one minus the water-vapour fraction, and the reference factor is (Pa/Pr)(Tr/Ta). It is a basis conversion, not a flow measurement or a stack-test method.

Ranks competing bids by weighted score across your criteria, with a robustness check on the weights. Use it to support a procurement decision.

Scores environmental, social and governance performance across the three pillars from a weighted questionnaire. Use it for a self-assessment of ESG posture; the questions are original and a score is not a rating.

Scores readiness against the HIPAA Security Rule safeguard areas from a weighted questionnaire. Use it for a self-assessment of security controls; the questions are original and a score is not evidence of compliance.

Scores cybersecurity readiness across the six NIST Cybersecurity Framework functions, Govern, Identify, Protect, Detect, Respond and Recover, from a weighted questionnaire. Use it for a self-assessment of security posture; the questions are original and a score is not evidence of compliance.

Scores a third-party vendor's risk across several domains from a weighted questionnaire, with a risk tier. Use it to triage vendor due diligence; the questions are original and a score is not a certification.

Draw an ordered outline on FloorCanvas, add up to five optional exclusion polygons, and calculate gross, excluded, and net area in one US/Metric app. Canvas edits remain local until Calculate is pressed; every reported area comes from the reviewed workbook.

Draw a floor plan on FloorCanvas with its rooms, windows and doors, set the wall height and each opening's height on the drawing or in the tables under it (and see them in 3D), and get the baseboard run and the baseboard and casing sticks to order, room by room, in US or Metric units. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Compare bids on the same scope of work. Each bid's price plus your allowance for every item it leaves out gives its normalized price; the bids are ranked by normalized price and then by duration, and the change orders after the award are added to the awarded bid to give the revised total, the revised duration and the margin against your estimate.

Estimate the concrete for slabs, strip footings, pads, piers, walls and solid stairs typed as element rows, or draw a slab on the page's drawing grid, exclude columns or drains and pour it through a 'Slab from the drawing' row, and get the concrete before and after waste, the bags and ready-mix loads with their costs, whether the pour is above a ready-mix threshold, and a rebar, mesh or entered reinforcement quantity, including a rebar takeoff across each slab's bounding rectangle. Typed dimensions and the concrete, bag, cost and reinforcement results are in US units; the drawing is in feet or metres and its areas in square feet or square metres. Over MCP the typed rows are the input; on the page, edits stay local until Calculate is pressed, and every figure comes from the reviewed workbook.

Estimate finish costs from a floor plan you draw: flooring, trim along the outline, wall finishes at your wall height, and doors and windows, each at your own unit price, with a regional factor and a contingency, and the total per square foot (or square metre) of floor.

Draw a deck on FloorCanvas, exclude a hot tub or a tree, mark its rails and stairs, set its height, and get the joists, beams, posts (a post at both ends of every beam, each cut to the deck height, with the post stock to buy) and footings with their concrete bags, the rim joists, the deck boards and screws (framing and boards follow the outline and its openings; shapes other than a plain rectangle are flagged for a site check), the railing posts and balusters for each rail run, and the risers, treads and stringers of each stair, in US or Metric units. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a slab or driveway on FloorCanvas, block out columns or drains, and get the concrete to order with waste, whether ready-mix is recommended, the trucks or bags it takes, and the length of control joints at your spacing, in US or Metric units. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a floor plan on FloorCanvas (rooms, interior walls, windows and doors), choose each room's floor (tile, plank, carpet, sheet vinyl or none) and its own product in the Materials panel, lay each room on the drawing (tiles and planks piece by piece, carpet and sheet vinyl in roll strips), and get the pieces laid and to buy, the boxes, the thinset and grout bags and the carpet and sheet vinyl to order, room by room and in total, in US or Metric units. A 3D view shows the walls and openings as drawn. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a floor plan on FloorCanvas (outline, interior walls, windows and doors), set the wall height and each opening's height, and get the studs, plate sticks, wall sheathing and nails to buy, with a header for every window and door, in US or Metric units. View the walls in 3D before you calculate. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a floor plan on FloorCanvas with its windows and doors, set the wall height, and get the exterior wall area net of openings, the attic area, the wall batts and attic bags to buy, and the R-value each surface reaches against your target, in US or Metric units. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

List a job's materials, labor, subcontractor and equipment costs line by line, set the overhead, profit and contingency rates and a sales tax on the materials or on the whole price, and get the direct cost, each markup, the tax and the total price to quote, with the markup and margin that price gives. As the requirement defines them, the markup and margin count the tax.

Draw a lot and the buildings and paved areas on it, say which are buildings, and get the lot coverage, the impervious share and the floor area ratio; coverage and the impervious share are checked against the limits you enter. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a floor plan on FloorCanvas (rooms, interior walls, windows and doors), set the wall height once and check each window's and door's height, lay the drywall sheets on the walls and ceilings with one button, and get the paint and primer to buy and the drywall sheets, compound, tape and screws, with each room's wall and ceiling areas, paint and sheets, in US or Metric units. A 3D view shows the walls and openings as drawn, and the laid sheets on the walls. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a patio on FloorCanvas, leave out columns, beds or planters, and get the pavers to order with pattern waste, the base gravel and bedding sand, the edge restraint along the outline and the polymeric sand bags, in US or Metric units. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a pool on FloorCanvas, leave out islands or planters, and enter the depth at each end and a fill rate to get the water volume in gallons or litres, the liner area, the coping length and the time to fill, in US or Metric units. The spreadsheet measures the perimeter from the drawn points; canvas edits stay local until Calculate is pressed, and every figure comes from the reviewed workbook.

Draw a roof on FloorCanvas, its ridges, hips and valleys and each facet's pitch, and get the true roof area, the squares, the shingle bundles and underlayment rolls, the starter strip, drip edge and ridge cap, the length of every roof line and a facet-by-facet schedule, in US or Metric units. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook.

Draw a one-storey house's outline on FloorCanvas, add its windows and doors, set the wall height and each opening's height, mark which doors are exterior, enter your siding's piece length, width and exposure, and lay the siding on the walls. Get the pieces and squares to order, the J-channel, corner posts and starter strip, with each wall's length, area and pieces laid, and each room's openings, in US or Metric units. A 3D view shows the walls and openings, and the laid courses up to a drawing size limit. Canvas edits stay local until Calculate is pressed; the drawing counts the pieces it lays, and every other figure comes from the reviewed workbook. The piece count is in pieces of the size you enter, so enter your product's.

Draw a lawn on FloorCanvas, leave out beds and hardscape, and get the sod rolls and pallets, topsoil and grass seed to order, in US or Metric units. Canvas edits stay local until Calculate is pressed; every quantity comes from the reviewed workbook.

Enter a stair's total rise, your target riser height and tread depth, and get the number of risers and treads, the actual riser height, the total run, and the stringer length and count. The riser height, the tread depth, 2R + T and, when you enter it, the headroom are checked against limits you can change. If you enter the run you have and the stair would not fit, the riser count is reduced to fit and flagged. US or Metric units.

Compares a synthetic replacement asset with the existing asset through incremental after-tax cash flows, calculates NPV and periodic IRR, and adds a probability-weighted abandonment or expansion decision option.

Applies a user-selected mean, median, or inclusive percentile of synthetic or user-entered trading-comparable or precedent-transaction multiples to a target operating metric, then bridges enterprise and equity value to an implied per-share value.

Discounts five annual unlevered free cash flows, adds a Gordon-growth or exit-multiple terminal value, and bridges enterprise value to synthetic equity value and implied value per diluted share.

Builds a five-period synthetic income statement, indirect cash-flow statement, and balance-sheet roll-forward from explicit operating, working-capital, capital-spending, financing, and tax assumptions.

Builds a synthetic seven-year operating and four-tranche debt schedule, applies mandatory amortization with an optional cash sweep, and bridges entry sponsor equity to exit gross MOIC and IRR.

Builds a transparent synthetic cash-and-stock consideration and financing bridge, applies recurring after-tax earnings adjustments, and compares pro forma diluted EPS with acquirer stand-alone diluted EPS.

Computes conduit fill from the conductors you enter against the 53, 31 and 40 percent limits, and recommends the smallest trade size that fits. Use it to check whether a conduit is within the fill limit.

Derives a motor's full-load current from its power, voltage, efficiency and power factor, then sizes the branch-circuit conductor, overload and disconnect. Use it for a first-pass motor circuit sizing.

Solves Ohm's law and the AC power triangle from any two known values among voltage, current, resistance and power. Use it for quick electrical calculations across single and three-phase circuits.

Sizes a transformer from the connected load, growth and diversity, and selects the smallest standard kVA rating with its primary and secondary full-load currents. Use it to choose a distribution transformer.

Calculates the voltage drop along a conductor run from its size, length, load current and material, reporting the drop in volts and as a percent against your limit. Use it to check a branch or feeder circuit and find the smallest size that stays within the allowed drop.

Sizes a copper conductor for both voltage drop and ampacity and reports which one governs. Use it to pick the smallest conductor that carries the load and stays within the allowed drop. Aluminium is not covered: the ampacity table this calculator carries does not include aluminium.

Computes ultimate and allowable bearing capacity of a shallow footing from derived bearing-capacity factors and a factor of safety. Use it for a first-pass foundation check.

Computes primary consolidation settlement and the time rate from soil compressibility and the stress increase. Use it to estimate foundation settlement.

Computes total stress, pore pressure and effective stress with depth, including a footing stress increase. Use it for geotechnical stress-profile calculations.

Computes active and passive earth pressure and the overturning, sliding and bearing checks for a retaining wall. Use it for a first-pass wall stability check.

Computes the factor of safety of a slope by the infinite-slope method, dry or with seepage. Use it for a first-pass slope stability check.

Classifies a soil to a Unified Soil Classification group symbol from its gradation and Atterberg limits. Use it to identify a soil for geotechnical work.

Calculates steady one-dimensional heat flux and heat rate through a constant-area plane wall of up to six user-entered layers in series. It can use known wall-surface temperatures or bulk-fluid temperatures with user-entered film coefficients.

Calculates the log mean temperature difference for ideal parallel-flow or counterflow terminal temperatures, rates heat duty from user-entered U and area, or solves the required area for a user-entered duty. It is a thermal rating screen, not an exchanger-selection or mechanical-design tool.

Calculates signed steady heat transfer, heat transfer per length, and cylindrical interface temperatures for a pipe wall plus optional insulation, with outside convection alone or outside convection and long-wave radiation.

Calculates the uniform-body temperature after an elapsed time or the finite time to a reachable target under a constant convective environment, while explicitly screening the lumped-capacitance assumption with Bi = h(V/A)/k.

Evaluates or sizes ideal sensible, latent, or combined sensible-plus-latent thermal storage and calculates source-side charge energy, delivered energy, and charge/discharge durations.

Calculates signed diffuse-gray radiative exchange for an entered two-surface enclosure network or for a small surface in a large isothermal enclosure.

Builds two transparent parallel heat-flow paths from a complete layer schedule, reports cavity, framing, and whole-wall thermal resistance, and optionally screens a degree-day retrofit payback.

Builds a fixed split-phase circuit schedule, separates continuous and noncontinuous current, applies a transparent 125 percent planning multiplier, routes each load to the correct panel leg, and reports the binding spare-capacity result. It can also take the existing load as a dwelling's calculated service load by the standard method, from its floor area, circuits and appliances, and then gives the load current and the next standard service size.

Calculates interior and exterior dew points with the Magnus relation, maps a steady-state temperature gradient through a complete assembly, and identifies the evaluated interface with the smallest dew-point margin.

Routes EVSE current from nameplate, restricted commissioning, or desired AC power; separates branch sizing from listed load-management allocation; derives conductor resistance from AWG geometry; checks voltage drop and panel legs; and estimates charging time with an optional high-SOC taper segment.

Routes Rational or direct inflow through eight full-pipe Manning candidates and exposes capacity, velocity, trench, gravel, and cost trade-offs.

Computes real and apparent running load, unrolls six motor-start groups, compares manual, priority-shed, automatic, and listed-EMS routes, checks split-phase leg loading and a site-derated generator candidate, and interpolates an editable manufacturer fuel curve.

Routes direct or sectioned roof area through Rational runoff, Manning gutter capacity, and independent outlet-capacity and spacing counts.

Combines eight irrigation groups into a simultaneous zone and audits flow, Hazen losses, pressure margins, precipitation matching, target depth, and cycle-and-soak schedule.

Derives AWG cross-section and temperature-adjusted conductor resistance, evaluates single-phase, balanced three-phase, or DC runs, and computes every editable conductor candidate against ampacity, running-drop, starting-drop, and cost criteria.

Runs a twelve-month storage balance across one entered tank or a fixed 21-capacity ladder and exposes reliability, overflow, reserve, and simple economics.

Builds a room-level steady-state heating and cooling load from envelope UA, outdoor airflow, solar, sensible, and latent gains, then screens user-entered equipment candidates against the active capacity targets.

Screens annual-energy, backup-with-recharge, or combined solar-plus-storage requirements against eight editable packages and exposes energy flow, power gates, first-year value, and discounted payback.

Intersects eight auditable generic pump curves with a routed discharge-system curve, then screens flow reserve, velocity, and optional cycling.

Calculates a whole-dwelling outdoor-air target from editable area and room rates, an entered target, or a CO2 mass balance, then checks installed airflow and a complete local-exhaust schedule.

Screens eight valve or pump events with routed velocity, elastic or entered wave speed, critical closure time, and Joukowsky pressure change.

Compares connected-load, separated-new-load, and metered maximum-demand routes for a before-and-after home electrification project while preserving an auditable twelve-row appliance and equipment inventory.

Compares user-entered window U-factors, solar-gain coefficients, and installed costs across heating, cooling, or combined scopes, then selects by annual energy cost, positive payback, or peak load.

Distributes a system's airflow room by room from each room's load and sizes the registers. Use it to balance supply airflow across a home.

Sizes an off-grid or backup battery bank from the load, autonomy, depth of discharge, round-trip efficiency and temperature derate. Use it to specify a battery bank.

Sizes ductwork by the equal-friction method, reporting velocity, friction rate and the required round or equivalent rectangular size, in IP or SI. Use it to size a duct run.

Estimates a building's sensible and latent heating and cooling loads from its envelope, occupancy and design conditions, in IP or SI. Use it for a whole-house load estimate and equipment sizing.

Computes moist-air properties such as wet-bulb, humidity ratio, enthalpy and dew point from two known properties, in IP or SI units. Use it for HVAC air-state calculations.

Models a solar PV system's production, bill savings and 25-year cash flow to report simple and discounted payback, return on investment, net present value and levelised cost of energy. Use it to evaluate a solar investment.

Combines concentration-duration entries into an actual-shift average, reference-period equivalent, entered-limit ratios, and a separate ceiling screen without embedding chemical exposure-limit data.

Combines up to 12 task-specific hand-arm vibration exposures into daily A(8), HSE exposure points, threshold utilization, and a dominant-task result.

Estimates a protected A-weighted level from an individual fit-test Personal Attenuation Rating (PAR) or OSHA Noise Reduction Rating (NRR) adjustment methods.

Compares the same multi-segment workday under OSHA permissible-exposure-limit, OSHA hearing-conservation, and NIOSH recommended-exposure-limit rules.

Calculates single-task Recommended Weight Limit and Lifting Index at the origin and, when significant destination control is required, at the destination.

Calculates measured and clothing-adjusted WBGT from natural wet-bulb, globe, and conditionally required dry-bulb sensor readings, then compares the result with user-entered thresholds.

Estimates the annual and monthly income a lump sum buys over a fixed term at an assumed interest rate, with payments at the start or the end of each year and an optional annual escalation. It reports the income, the total paid over the term, and the years of payments needed to return the premium. It prices a term certain, so it carries no mortality pooling and no insurer expense loading, and a real quote will be lower.

Works out what to trade to bring a portfolio back to its target weights, and answers two further questions: whether the drift is far enough past your tolerance band to be worth trading on at all, and how much of the job a contribution directed at the underweight holdings can do without selling anything. Use it before placing trades, to see what a sale would cost you and whether new money can spare you one.

Works out the monthly payment on a car loan built from the whole deal: the sales tax charged under your state's own rules for a trade-in and a rebate, dealer and government fees, a trade-in with any debt still owed on it, and a manufacturer's rebate set against a promotional rate. Use it to see what the loan really costs, how many months you would owe more than the car is worth, and what the 2025 car-loan interest deduction is worth at your own tax rate and income.

Prices a credit card balance transfer against staying where you are: the interest each card charges over the whole payoff, the fee the new card takes, what the move is worth once that fee is counted, the first month it has cost you less than staying, and the balance still owed on the day the promotional rate ends. It also tabulates the saving across eleven monthly payments and eleven promotional lengths, so the part of the answer you control is separated from the part the offer decides.

Sorts a household's own monthly spending lines into needs, wants and savings and sets each against the 50/30/20 rule, on an income counted the way the rule's authors counted it: take-home pay plus what the pay slip already takes for insurance and retirement. It reports how far each bucket sits from its target in dollars, which band the needs share falls in against the 50 percent ceiling and the 35 percent safety zone, and the income at which today's needs would fit the ceiling. Use it to see which bucket is out of line and by how much, rather than only dividing one income three ways.

Compares financing a purchase now with setting the same monthly budget aside and paying cash later, once the savings meet the price of that month, which rises or falls at the yearly rate you choose. Use it to see how long saving takes, what each path costs, and which one leaves you with more once both own the item.

Works out the federal tax on one sale by stacking the gain on top of your other taxable income and charging each rate layer it reaches at that layer's own rate, so a gain that straddles two layers is priced as two pieces rather than at one flat rate, with the net investment income surtax on the lesser of the gain and the income above its threshold. Use it to see what a sale actually costs, how much of the gain lands in each rate band, and what the same sale would cost on either side of the twelve-month holding period.

Prices leasing a car and buying the same car over the years you would keep it: the lease by the Federal Reserve's formula, with your state's own lease-tax method, repeated for as many leases as the years cover; the purchase with a loan and a sale at a value tied to the lessor's own residual and moved for your mileage. It says which costs less over your years and by how much, and shows year by year, up to fifteen years, which choice would have cost less, with the first year buying costs no more than leasing. Use it to compare a lease offer with a loan on the same car rather than one monthly payment with another.

Prices giving the same amount to charity every year against giving several years of it at once, under the 2026 rules: the half-percent-of-income floor that is charged once a year instead of once and is lost outright rather than carried forward, the ceiling on a large cash gift, the cash deduction a non-itemizer keeps and forfeits by using a donor-advised fund, and the overall limitation on a high income. Use it to decide whether bunching is worth doing at your income and your level of giving, and to see the answer when it is not.

Judges a second income on what it actually leaves after the taxes it alone attracts, the childcare it makes necessary and the costs of going to work, with the dependent care credit or a dependent care FSA priced from the 2026 schedule rather than at its headline rate, and then reports the weekly childcare cost and the salary at which the job stops paying. Use it when one earner is deciding whether a job is worth taking or keeping while children are in paid care.

Itemises what you will be asked to pay at closing, separated into lender fees, third-party fees and prepaid items, and adds the down payment to give the cash you actually need. The split is the point: only lender fees move much when you change lender, and prepaid tax and insurance are money you owed anyway rather than a cost of borrowing.

Prices every year of study at the price it will actually be paid at rather than multiplying one inflated year, projects a 529 account forward to the day study begins, and reports the gap three ways: the share of the cost the account covers, the amount still to find, and the level monthly contribution that would close it exactly. It also prices what the account's tax treatment is worth as a number: the growth that is never taxed plus the state deduction where a state offers one.

Projects a balance forward at a rate you quote, adding the interest as often as the account really adds it, from once a year to continuously, and reports the effective annual rate that frequency actually pays. It also compares the answer against the same money at simple interest, so the part of the balance that is compounding rather than deposits is a figure rather than a feeling, and puts the whole projection on a grid of rates and horizons.

Compares the cost of living in two states with the federal government's own regional price parities, and gives the salary that keeps the same standard of living. Your share of spending on rent or a mortgage re-weights the comparison, because rents differ between states far more than the rest of spending taken together. Optional state income-tax rates and a saving share turn it from a price comparison into a pay comparison.

Rebuilds what one child costs from the age you enter through 17 out of the published survey's own parts, the age band, the household income group, the region and the adjustment for how many children there are, and states it both in today's dollars and in the dollars of each year the money is spent, split into the seven things it goes on. Use it to replace a single national headline with a figure for your own household, and to see how much of the total is the early years, the later ones and inflation.

Runs a credit card balance to zero twice, once at a fixed monthly payment you choose and once at the issuer minimum stated the way the large issuers state it, as the month's interest plus a percentage of the balance with a money floor underneath, and reports the months, the interest and the total paid on each path beside what the difference is worth. Use it to see what a statement's minimum payment actually costs over its whole life and what a fixed payment buys instead.

Prices your debts as they stand against one consolidation loan, month by month, with the origination fee counted and the whole life of both routes compared. It reports both monthly payments, both total costs and the two differences, and it is built around the case where a lower monthly payment over a longer term costs thousands more in the end.

Runs both debt payoff orders side by side on the same money: the highest rate first, and the smallest balance first, over up to ten debts with their own rates and minimum payments. It reports what each order costs in interest, how long each takes, and the month each one clears its first debt, so the case for clearing a small debt early is a number rather than a claim, and it tabulates the payoff across a grid of extra payments and rate changes.

Works out both debt-to-income ratios a lender measures you by, housing as a share of gross monthly income and all debt as a share of it, and puts them against every published guideline at once. It names the strictest guideline your ratio still clears, the largest new monthly payment each guideline would admit, and how much of that room is left once a loan you are considering is counted.

Prices a high-deductible health plan against a low-deductible one over the same year of care, crediting the high-deductible side with all three of its advantages: the lower premium, the employer contribution into a health savings account, and the tax saved on your own contribution. It reports which plan costs less at the care you expect, the billed spend at which the two would cost the same, and the most a single year can cost under each.

Works out what a group long-term disability plan would actually leave you with each month after the tax an employer-paid benefit attracts, measures that against the spending that cannot stop, and splits the difference into the part a supplemental individual policy could close and the part no policy will cover, because insurers limit total replacement across every policy to a share of income. Use it to see whether cover described as replacing sixty percent of your salary would pay your bills, and how much cash the wait before it starts would take.

Compares investing a sum all at once against feeding it in over several months, on a return you supply, and reports what each is worth at the end, how much the waiting costs and what it saves if the market falls instead. It also runs the comparison across a band of returns you are unsure about and reports how often each way comes out ahead.

Sizes an emergency fund in two layers, a reserve for the surprise bill that far more households meet than a layoff, plus months of only the part of essential spending that other income would not cover, then works out how long a savings account's APY takes to build it and whether the months of cover outlast a typical spell of unemployment. Use it to set a target you can reach and to see what the monthly amount and the rate change about when you get there.

Prices two different ways of paying a debt off sooner and keeps them apart: a recurring extra every month and a single lump sum, each run as its own full schedule beside the baseline and then both together, with the months and the interest each one saves. It also reports the rate the money earns by going to the debt, which is the debt's own rate, and tabulates the interest saved across eleven sizes of extra payment and eleven rates so the diminishing return is visible rather than asserted.

Computes the invested balance that supports your spending at the withdrawal rate you plan to use, then finds how many years of saving and real growth it takes to reach it. It reports your savings rate, your age on arrival, and how much sooner you would arrive saving half as much again. Growth is a single average real return, so it says nothing about the order in which returns arrive.

Reports equity, the first-mortgage loan-to-value ratio and the combined ratio across every lien, and how much more you could borrow before reaching the limit a lender applies. It reports both mortgage-insurance thresholds and which value each rule is measured against, because automatic termination uses the original price while cancellation on today's value has to be requested.

Prices a health savings account on both of its sides: the tax a year's contribution avoids, split into the three layers that make it up, because federal income tax always applies, state income tax often does not and payroll tax is saved only where the money goes in through an employer's payroll plan and only below the Social Security wage base; and the balance the account reaches over the years you keep it, under either way of paying for care. Use it to see what a contribution is actually worth to you, whether an employer's money has pushed you over the shared limit, and what keeping the receipts rather than spending from the account is worth over a long horizon.

Restates an amount of money between any two years from 1913 on the official consumer price index. It reports the compound inflation rate over the period, beside the average of yearly rates that overstates it. It then projects what the same amount will buy in the years ahead at an inflation rate you assume, held as cash or earning a savings rate.

Prices an investment fee as what it costs rather than as what it is billed: the same plan is run twice, once with no fee and once with the fees you pay, and the gap between the two balances is split into the fees charged and the growth those fees never made. A one percent annual charge over thirty years costs about two and a half times the fees actually taken and a quarter of the final pot, and it also prices a second fee against yours so an active fund and a tracker can be compared in one place.

Works out how much life cover a household needs by the DIME method, adding debts, years of income, the mortgage payoff and the cost of education, taking off the cover and savings already in place, and reporting the income leg both the way insurers state it and discounted to the lump sum that would actually pay it out. Use it to see how far a plain DIME total and the ten-times rule of thumb sit from each other, and what the cover needed would cost in premium at the age entered.

Works out the monthly payment on a plain amortising loan and prints the schedule it produces year by year: how much of each year's payments went to the balance, how much went to interest, and what was still owed at the end of it. It also reports the share of the first year's payments that is interest and the year in which principal finally overtakes interest, prices an optional extra monthly payment beside the schedule, and tabulates the payment across eleven rates and eleven terms so the two numbers on an offer letter can be read against each other.

Works out the 2026 federal income tax on a household's income and reports the rate on the next dollar twice, as the statutory bracket rate and as the rate actually faced once a deduction that is being withdrawn is counted, and the rate on every dollar three times, once against each of the three bases the income tax is divided by: taxable income, adjusted gross income, and income before any deduction. Use it to see which rate you are being quoted, how many dollars of room are left before the next bracket, and how much of your income the payroll tax takes alongside the income tax.

Works out the most you can pay for a home from your income, your existing debts and the two qualifying ratios a lender applies, and says which of the two binds. Because property tax scales with the price the model is solving for, the affordable price is solved as a fixed point rather than divided out, which is the step that makes the answer consistent with the payment it implies.

Works out the full monthly cost of a mortgage -- principal, interest, property tax, homeowner insurance, association dues and mortgage insurance -- and stops charging the mortgage insurance at the month the loan reaches 78 percent of the original price, where it terminates. It reports that month, the total insurance actually paid, and what the payment drops to afterwards.

Prices discount points as an investment with a horizon: what they cost, what they save each month, when the saving has repaid them, and what they are worth over the time you expect to keep the loan. It counts the extra principal the lower rate pays down by then, which is worth four figures on an ordinary loan, and can restate the whole trade as a present value.

Compares a shorter mortgage with a longer one on the same amount: the payment and total interest of each, and then a further comparison -- on the day the shorter loan is paid off, what is still owed on the longer one against what the payment difference would have grown into if invested. It also says when the longer loan would be gone if you simply paid the shorter loan's payment on it.

Values a pension offered as a monthly payment against a lump sum alternative by discounting the payments at the return you believe you could earn on the cash, including any annual increase and a survivor benefit. It reports which is worth more today and the discount rate at which the two are equal, and it says so plainly when the pension is worth less than the lump sum at every non-negative return, because then no such rate exists.

Turns a nominal return into what it is actually worth once inflation and, optionally, tax have taken their share, using the Fisher relation rather than the usual shortcut of subtracting inflation from the return. It reports the exact real return beside the shortcut and the gap between them, the return needed merely to keep pace after tax, what a starting amount becomes on a statement against what it will buy, and a weighted grid of both rates that says how often the money gains purchasing power at all.

Says how many months a refinance takes to repay what it costs, measured against the term remaining on the loan you have rather than a fresh full term, so a longer new loan cannot disguise re-extension as a saving. It reports the years added to the term as its own figure, compares total remaining cost under each loan, and handles costs rolled into the balance, where there is no break-even month at all.

Compares renting with buying on the net worth each leaves you with at the end of the period you expect to stay, rather than on monthly cost. The renter's down payment and every month of saved cost are invested at a return you set, the owner's spare cash is invested in any month rent costs more, and the sale at the end pays selling costs and repays the loan. It also reports the month from which buying goes ahead and stays ahead.

Projects the required minimum distributions from a retirement account year by year from a life-expectancy divisor that falls as you age, and reports the largest single year, the total distributed and the balance left at the end. Enter a tax rate and it also reports the tax on the distributions. The divisors are illustrative inputs you take from the governing table yourself; none is reproduced here.

Works out what you and your employer put into a workplace retirement plan over a year from the share of pay you defer, applies the plan's tiered match, and reports any employer money you are forfeiting. Use it to find the deferral that captures the whole match. The deferral and catch-up limits are illustrative inputs you set yourself, not a reproduced schedule.

Runs a retirement balance forward year by year against a withdrawal that rises with inflation, and reports whether the money lasts, the year it would first fall short, and the withdrawal that would last exactly the planned period. Use it to test a four percent rule or any other starting withdrawal against your own return and inflation assumptions.

Projects what your retirement savings grow to by the age you plan to stop working, reported in today's money as well as the money of that year, and the annual income the balance supports at your chosen withdrawal rate. Enter a target income and it also reports the shortfall and the extra annual saving that would close it.

Compares converting a traditional balance to a Roth against leaving it alone, paying the conversion tax now and taxing the untouched balance when you eventually draw it. It reports which comes out ahead, the outside cash the conversion needs, and the future tax rate at which the two are equal. It models one conversion in isolation, not the bracket, surcharge and credit effects of adding the converted amount to a year's income.

Puts the rule of 72 beside the exact doubling time for your rate and compounding frequency, and reports how far the rule is off in years and as a share, the numerator that would be exact at your rate, and the range of rates over which the rule stays within a quarter of a year. It also gives the exact time to triple and to grow tenfold, and tabulates the error across a grid of rates and numerators so the safe region can be seen rather than assumed.

Works out what you must put aside each month to reach a savings goal by a deadline, given what you have already saved and the return you expect. It then does the two things a single division cannot: it restates the goal at the deadline when the thing you are saving for gets more expensive, and it runs the whole plan again across a spread of returns, so the answer arrives as a chance of getting there and a range of outcomes rather than as one confident number.

Applies the early-claiming reduction and the delayed-retirement credits to the monthly benefit you would receive at full retirement age, then compares two claiming ages on the total received by a planning age and on the age at which the later claim overtakes the earlier one. The adjustment is derived from the published monthly rates rather than read from a table, and the benefit amount is yours to supply from your own statement.

Prices a student loan on the repayment term you choose and puts the ten, twenty and twenty-five year terms beside it from the same balance and rate, so the cost of a longer plan is a number rather than a feeling. It also prices what happens before repayment starts: interest that builds up during school, a grace period or a deferment, and what it costs once it is added to the balance and begins earning interest of its own. Income-driven repayment is not modelled and the workbook says so.

Estimates each paycheck from a salary with the IRS's 2026 withholding tables, applies each pre-tax deduction only to the wages it actually reduces, and sets the year's withholding beside the year's tax so the refund or balance due is visible before you file.

Prices a harvested investment loss as the deferral it is: the tax it saves this year under the netting order the Internal Revenue Service sets out, the carried-forward remainder valued at the annual limit a year at a time, and against those the extra tax due when the replacement position is sold with a basis lower by exactly the loss. Use it to see how much of the benefit is a permanent saving from the gap between the rate saved today and the rate paid later, and how much is only timing.

Works out what a car costs to own over the years you keep it, in the six categories AAA counts (depreciation, loan interest, fuel or electricity, insurance, upkeep, and taxes and fees), year by year, with depreciation moved by your mileage the way AAA moves its own average, and sets the result beside AAA's published average for the class at your miles. Use it to see the cost a year, a month and a mile of a particular car, price and way of driving, and which categories make it.

Compares a traditional and a Roth contribution of the same size by growing each forward and taxing it on the rules that apply to it, so the two are judged on what you keep rather than on what goes in. It reports which comes out ahead and the future tax rate at which they are equal, and it can invest the traditional contribution's up-front tax saving in a taxable side account, so the two routes can also be compared at equal cost.

Enter your crypto purchases and the price today, and see your average cost, the units you hold, your gain or loss and how much of it is on purchases held more than one year, and compare selling a share of your units first in, first out, last in, first out or highest cost first. Then simulate a fixed purchase every 1, 2 or 4 weeks across 100 weekly price paths inside a seeded, reproducible workbook, and see the range of the plan's value by week and the chance that it ends below what it put in. Gains and holding periods, not the tax on them. Estimates for education, not advice.

Simulate 100 market futures for a retirement plan whose mix of equities, bonds and cash follows a glide path by age, inside a seeded, reproducible workbook, and see the share of futures in which the money lasts to the end age, the equity share today and the spread of balances by age. Each year is drawn with the average return and volatility of that year's mix, less fees; contributions and withdrawals rise with inflation. Estimates for education, not advice.

Simulate 100 market futures for yearly contributions to a 529 plan or an HSA inside a seeded, reproducible workbook, and see the range of balances when the money is withdrawn, the tax the contributions save, and how far the account comes out ahead, after tax, of an ordinary taxable account that costs you the same each year. Tax is shown at contribution, on growth and at withdrawal for both. Estimates for education, not advice.

Find the Kelly bet, the share of the bankroll that makes it grow fastest over many bets, from your chance of winning and the odds, size your bet as a share of it, and simulate 100 seeded sequences of 200 bets at full, half and quarter Kelly and at your size inside a reproducible workbook: see how often each falls further from a peak than you can accept and how the bankroll spreads. Estimates for education, not advice.

Simulate 100 monthly price paths for a position bought partly with a margin loan inside a seeded, reproducible workbook, and see the chance of a margin call within the horizon, how far the value can fall today before a call, the share price that triggers one, the leverage and what the loan costs a year, with a price fall, no change and a rise compared with and without the loan. Margin is checked at each month end. Estimates for education, not advice.

Simulate 100 market futures for a retirement plan inside a seeded, reproducible workbook and see the share in which the money lasts, the spread of balances year by year, when failures happen, and how a smaller withdrawal, a later start or lower volatility moves the odds. Returns are lognormal with the average and volatility you enter, less fees; withdrawals rise with inflation. Estimates for education, not advice.

Work out the cash flow, cap rate, cash-on-cash return, debt service coverage and return on the money invested of one rental property, before income tax, then simulate 100 futures of rent growth, vacancy and appreciation inside a seeded, reproducible workbook to see the spread of returns, the share returning less than the mortgage rate and the share with a year of negative cash flow. Estimates for education, not advice.

Converts drainage or water fixture units to peak demand and a recommended pipe size. Use it for a first-pass plumbing pipe sizing.

Sizes natural-gas pipe by the longest-length method from the required capacity in cubic feet per hour and the allowable pressure drop. Use it for a first-pass gas pipe sizing.

Computes thermal expansion, guided-cantilever loop sizing and support spacing by stress and deflection. Use it for pipe expansion and support layout.

Computes pipe pressure drop and head loss by Darcy-Weisbach with the Colebrook friction factor, alongside Hazen-Williams, with velocity and Reynolds number. Use it to check a liquid pipe run.

Computes total dynamic head, hydraulic and brake power and the NPSH margin for a pump, with the system curve. Use it to select and check a pump.

Computes full and partial volume for horizontal and vertical tanks with various heads, and a dip chart. Use it to gauge tank contents.

Builds an eight-period construction draw schedule with selectable debt/equity priority, debt eligibility, beginning or average debt interest basis, day-count convention, commitment fees, IDC capitalization, and facility/commitment caps.

Builds a ten-year project debt schedule under target-DSCR, straight-line-principal, or level-debt-service routes, with beginning or noncircular average debt interest, maturity routing, LLCR, balloon, and covenant-breach diagnostics.

Builds a ten-year energy-revenue schedule with cumulative degradation, capacity factor, availability, curtailment, contract term and share, escalated or entered contract prices, growing or entered merchant prices, compensation routing, and merchant-tail isolation.

Allocates ten-period equity contributions and project distributions under pro rata ownership or a preferred-return waterfall with simple/compound accrual, return of capital, optional GP catch-up, carried-interest residual split, investor cash flows, MOIC, and deterministic unique-root periodic IRRs.

Links construction sources and uses to an eight-period project cash waterfall with selectable funding priority, cash-tax treatment, scheduled debt service, optional sweep, reserve retention, and equity distributions.

Builds a ten-year synthetic cash-tax schedule with straight-line, declining-balance, or entered depreciation; full or EBITDA-capped interest deduction with carryforward; limited or unrestricted modeled NOL utilization; and visible basis and NOL roll-forwards.

Builds a binomial acceptance-sampling plan with its operating characteristic curve, producer and consumer risks and average outgoing quality. Use it to design or check a lot inspection plan.

Computes X-bar and R control limits from your subgroups using derived control-chart constants, and flags out-of-control points. Use it to set up a control chart from sample data.

Scores failure modes by severity, occurrence and detection to a risk priority number, with a severity gate for high-harm modes. Use it to rank and triage risks in an FMEA.

Runs a Gage R&R measurement-system analysis by ANOVA, reporting repeatability, reproducibility, percent study variation and the number of distinct categories. Use it to judge whether a gauge is adequate.

Computes the process capability indices Cp, Cpk, Pp and Ppk against your specification limits, with the estimated defect rate. Use it to judge whether a process meets its tolerance.

Converts between defects per million opportunities, yield and sigma level, including the 1.5 sigma shift. Use it to express process performance on the Six Sigma scale.

Projects an entered test-condition life parameter to a use temperature with the Arrhenius acceleration model and an exponential or Weibull life distribution.

Converts known MTBF or observed operating time and failures into constant-rate mission reliability, life metrics, and exact one-sided confidence bounds.

Plans exact zero-failure exponential accumulated-time or binomial pass/fail demonstrations without copied test-plan tables.

Evaluates a two-state repairable system with constant failure and repair rates, including transient, average, and steady-state availability.

Calculates independent-component series, parallel, or identical-component K-out-of-N mission reliability without external reliability tables.

Evaluates a two-parameter Weibull life model from an entered shape, characteristic life, time, and target failed fraction.

Rates an open-belt drive from its pitch diameters: ideal and actual speed ratio under an entered driven-speed loss, belt speed, approximate belt length and smaller-pulley wrap angle from external-tangent geometry, and delivered power, shaft torques and input-side effective belt pull at an entered overall efficiency. It is a drive-performance screen, not a belt selection or tension design.

Rates one involute spur-gear mesh at common pitch: tooth-count ratio, driven speed, driven pitch diameter, output torque at an entered mesh efficiency, and the tangential, radial and normal pitch-point force magnitudes. External and internal meshes differ in rotation sense and centre distance. It is kinematics and mesh statics, not a gear-strength or AGMA rating.

Computes isentropic discharge temperature, specific work and shaft power for an ideal gas from the pressure ratio and the heat capacity ratio, either on the ideal isentropic branch or adjusted for an entered isentropic efficiency. Gas properties stay user inputs; it is a thermodynamic screen, not a compressor selection or a real-gas calculation.

Scales a known pump or fan duty point to a new speed with the affinity laws: flow with the speed ratio, pressure rise with its square, shaft power with its cube. The target may be entered as a speed or as a nonnegative speed ratio. It assumes unchanged geometry and comparable similarity conditions, so it is a screening scaler, not a substitute for a vendor performance curve.

Solves any one of shaft power, torque or rotational speed from the other two, then rates a solid or hollow circular shaft in torsion: polar moment, maximum shear stress, angle of twist, torsional stiffness and maximum shear strain. It is a strength-of-materials screen, not a fatigue, critical-speed or shaft-design determination.

Computes the steady-state response of a linear single-degree-of-freedom oscillator to harmonic force or harmonic base displacement: natural frequency, damping ratio, frequency ratio, magnification or transmissibility, response amplitude, phase lag, and peak velocity and acceleration. It is a response screen, not a vibration-acceptability determination.

Computes asphalt tonnage from paved area, thickness and mix density, with waste and whole-load ordering. Use it to order paving material.

Computes deflection, moment and shear for a simply supported or cantilever beam under point and distributed loads, with span-over-deflection checks. Use it for a first-pass beam check.

Draw a cross-section, or send its outline and up to five inclusions as rows in FEET (US) or METRES (Metric), not inches, with Y running down; give each inclusion's modular ratio n (its elastic modulus over the outline material's) and a bending moment in kip·ft (Metric: kN·m), and get the transformed section's area, centroid, moments and product of inertia, principal axes, section moduli, radii of gyration and each material's highest and lowest bending stress. The section figures are in in, in², in³ or in⁴ (Metric: mm, mm², mm³ or mm⁴), the stresses in ksi (MPa) and the principal angle in degrees; the drawing's own areas (gross, net and each inclusion) are in sq ft (m²). The workbook trusts the drawing to keep inclusions inside the outline and apart, and checks it cheaply itself: an inclusion outside the outline or on top of another is refused, but not every partial overlap or self-crossing drawing.

Computes cut and fill volumes by the average-end-area method with shrinkage and swell, plus the haul and mass balance. Use it to estimate earthwork quantities.

Computes peak stormwater runoff by the rational method from a weighted runoff coefficient, rainfall intensity and drainage area, with time of concentration. Use it for small-watershed drainage design.

Draw a cross-section, or send its outline and up to five holes as rows in FEET (US) or METRES (Metric), not inches, with Y running down, and get its area, centroid, moments and product of inertia, principal moments and angle, elastic and plastic section moduli, radii of gyration, an approximate torsion constant and its steel weight per length. The section figures are in in, in², in³ or in⁴ (Metric: mm, mm², mm³ or mm⁴), the weight per length in lb/ft (kg/m) and the principal angle in degrees; the drawing's own areas (gross, net and each hole) are in sq ft (m²). The workbook trusts the drawing to keep holes inside the outline and apart, and checks it cheaply itself: a hole outside the outline or on top of another is refused, but not every partial overlap or self-crossing drawing.

Computes the axial capacity of a steel column across both buckling branches, in LRFD and ASD, against the applied load. Use it for a first-pass column check.

Sizes a storm drainage pipe by Manning's equation, reporting full-flow capacity, velocity and the recommended diameter. Use it to size gravity storm pipe.

Computes the economic order quantity that minimises ordering and holding cost, with the reorder point and quantity price breaks. Use it to set order sizes for inventory.

Sizes contact-centre staffing with the Erlang C model, reporting the agents needed for a service-level target with occupancy and wait probability. Use it for call-centre workforce planning.

Determines billable weight, freight class by density and the shipment cost. Use it to estimate less-than-truckload freight charges.

Builds the landed cost per unit from the invoice price plus freight, duty and other fees, with the cost breakdown. Use it to price imported goods.

Computes overall equipment effectiveness as the product of availability, performance and quality from a week's production data. Use it to measure and diagnose equipment productivity. Calendar utilisation and TEEP are measured against all 168 hours in the week, so a single day of data reports a low figure by construction.

Computes safety stock and reorder point from demand and lead-time variability at a target service level, with the fill rate. Use it to set inventory buffers.

Prices a synthetic fixed-rate bullet bond from yield or solves yield from an observed dirty price, then exposes coupon cash flows, duration, convexity, dollar duration, and DV01.

Locks the domestic-currency value of a synthetic foreign receivable or payable through a forward contract, a borrow/invest money-market replication, or an explicit comparison of both routes.

Values synthetic fixed and floating coupon legs on an entered discount curve, routes floating coupons through entered forwards or discount-factor-implied forwards, and computes par rate, coupon DV01, and a parallel market-curve bump.

Rolls four synthetic loan tranches through mandatory amortization and priority cash sweeps, calculates fixed or benchmark-plus-spread interest, and tests leverage, interest-coverage, and debt-service-coverage thresholds over seven visible years.

Prices a synthetic call or put through Black-Scholes or a recombining Cox-Ross-Rubinstein tree, supports European and American tree exercise, and exposes analytic or tree-derived price sensitivities.

Bootstraps eight annual discount factors from a synthetic mix of zero-rate and par-coupon instruments, derives zero and one-year forward rates, and interpolates a target maturity through either log discount factors or zero rates.

Calculates daily BOD5, CBOD5, or COD loading divided by active MLVSS inventory derived from volume and MLVSS, volume and MLSS with a volatile fraction, or a directly entered MLVSS mass.

Calculates required dry or liquid chemical feed from flow and target dose, or back-calculates achieved dose from an actual feeder rate, with optional user-entered capacity screening.

Calculates achieved chlorine CT from a minimum residual and direct or process-unit T10, solves the T10 required for a user-entered CT target, or sizes a minimum effective volume from peak flow and a user-entered baffling factor.

Calculates surface overflow rate and solids loading rate for in-service clarifiers using explicit geometry, flow, unit-system, and solids-stream choices.

Draw a channel cross-section on FloorCanvas, type the water depth, slope and Manning's n, and get the flow area, wetted perimeter, hydraulic radius, top width, Manning flow rate and mean velocity, in US or Metric units, with a curve of flow rate against water depth. Canvas edits stay local until Calculate is pressed; every figure comes from the reviewed workbook, which reads Y as running down the page, refuses an outline whose edges cross, and marks with CHECK any part under the water that faces down.

Calculates standard 30-minute sludge volume index and companion settling indicators from either one 30-minute observation or a fixed 5-60 minute settling curve.

Calculates actual SRT/MCRT from system inventory and measured solids exits, or solves the nonnegative waste flow required for an entered target SRT on a consistent total- or volatile-solids basis.