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finance-business · personal-finance · retirement-accumulation

Retirement Savings Projection Calculator

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.

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Calculator overview

Inputs and outputs

This summary comes from the calculator's published input and output contract.

Inputs

Annual Contribution (required)
About this input

What you put in yourself over a year, before any employer money. If you contribute monthly, enter twelve times the monthly figure.

Unit currency/yr Default 12000 Range At least 0
Contribution Timing (required)
About this input

Whether contributions land at the end of each year or the start. Starting-of-year contributions earn one extra year of return.

Default End of year Allowed End of year, Start of year
Current Age (required)
About this input

Your age today, in whole years. With the planned retirement age it sets how long the money has to grow.

Unit years Default 35 Range 18 to 80
Current Balance (required)
About this input

What is in your retirement accounts today, across all of them, in the currency you want the answer in. Enter 0 if you are starting from nothing.

Unit currency Default 50000 Range At least 0
Employer Contribution (required)
About this input

What your employer puts in over a year, including any match. Enter 0 if there is none.

Unit currency/yr Default 4000 Range At least 0
Expected Return (required)
About this input

The average annual return you expect on the balance, expressed as a percentage, before inflation and after fees.

Unit fraction Default 0.06 Range 0 to 0.25
Inflation Rate (required)
About this input

The average annual inflation you expect, expressed as a percentage. It is what converts the projected balance into today's money.

Unit fraction Default 0.025 Range 0 to 0.15
Retirement Age (required)
About this input

The age at which you plan to stop contributing and start drawing an income. It must be later than your current age.

Unit years Default 65 Range 50 to 80
Salary Growth Rate (required)
About this input

The percentage by which your contribution rises each year. Most calculators hold the contribution flat, which understates the result; enter 0% to match them.

Unit fraction Default 0.02 Range 0 to 0.25
Target Retirement Income
When omitted Blank
About this input

Optional. The annual retirement income you are aiming for, in today's money. Leave it blank for a projection alone; fill it in to also see the gap and the extra saving that would close it.

Unit currency/yr Default Not set Range At least 0
Withdrawal Rate (required)
About this input

The percentage of the balance you plan to draw in the first year of retirement. Four percent is the conventional starting point, not a rule.

Unit fraction Default 0.04 Range 0.001 to 0.2

Outputs

Extra Annual Saving
About this output

The additional amount per year that would close the gap by your retirement age. Zero when the target is already met, and blank until you enter a target.

Unit currency/yr
First Year Income
About this output

The income the balance supports in the first year of retirement, at your withdrawal rate, in the money of that year.

Unit currency/yr
First Year Income Today
About this output

The same first-year income in today's money.

Unit currency/yr
Income Gap Today
About this output

Target income less projected income, in today's money. Positive means a shortfall. Blank until you enter a target.

Unit currency/yr
Investment Growth
About this output

The projected balance less the opening balance and everything paid in. The year this overtakes contributions is the point compounding takes over.

Unit currency
Model Status
About this output

Reads OK, or explains why the inputs are not valid or why the answer deserves a second look.

No unit declared
Projected Balance
About this output

The balance at retirement, in the money of that year.

Unit currency
Projected Balance Today
About this output

The same balance expressed in today's money, which is what tells you what it will buy.

Unit currency
Real Return Rate
About this output

The expected return after inflation, computed exactly as (1 + return) / (1 + inflation) - 1. If it is at or below zero the balance loses purchasing power.

Unit fraction
Total Contributed
About this output

Everything paid in over the period, yours and your employer's, with the salary growth applied. It excludes the balance you started with.

Unit currency
Years To Retirement
About this output

Whole years between your current age and your planned retirement age.

Unit years
This page is provided by LogicCommons for informational purposes only. Results are model outputs computed from the inputs you supply and are not financial, investment, tax, accounting, or legal advice, and no advisory relationship is created. Verify all inputs and results independently before relying on them in any decision.

LogicCommons is in beta. If a result, label, or reference looks wrong, tell us here; we read every message.

Methodology

Purpose and model boundary

Use this calculator to project a retirement balance from today's savings and a stream of future contributions. It reports the retirement balance in future dollars and today's purchasing power, plus the first-year income implied by your withdrawal-rate assumption.

The model assumes smooth annual growth and constant inputs. It excludes volatility, taxes, fees, employer vesting, contribution limits and changes in employment, saving or spending before retirement.

Inputs and units

Input Unit Accepted range What it means
Retirement Age years 50 to 80 The age at which you plan to stop contributing and start drawing an income. It must be later than your current age.
Inflation Rate percentage 0–15% The average annual inflation you expect. It converts the projected balance into today's purchasing power.
Salary Growth Rate percentage 0–25% The percentage by which the annual contribution rises each year. Enter 0% to keep contributions level.
Withdrawal Rate percentage 0.1–20% The percentage of the retirement balance you plan to draw in the first year. Four percent is a common reference point, not a rule.
Target Retirement Income $/year 0 or more Optional. The annual retirement income you are aiming for, in today's money. Leave it blank for a projection alone; fill it in to also see the gap and the extra saving that would close it.
Expected Return percentage 0–25% The average annual return you expect on the balance, before inflation and after fees.
Contribution Timing End of year; Start of year Whether contributions land at the end of each year or the start. Starting-of-year contributions earn one extra year of return.
Annual Contribution $/year 0 or more What you put in yourself over a year, before any employer money. If you contribute monthly, enter twelve times the monthly figure.
Current Age years 18 to 80 Your age today, in whole years. With the planned retirement age it sets how long the money has to grow.
Employer Contribution $/year 0 or more What your employer puts in over a year, including any match. Enter 0 if there is none.
Current Balance $ 0 or more What is in your retirement accounts today, across all of them, in U.S. dollars. Enter 0 if you are starting from nothing.

Governing relationships

The existing balance grows to PV (1 + r)^n. Contributions that start at C and grow at g have future value C ((1 + r)^n - (1 + g)^n) / (r - g), using C n (1 + r)^(n-1) when r equals g. Total undiscounted contributions are C ((1 + g)^n - 1) / g, or C n when growth is zero. To express the result in today's money, the calculator uses the exact real return (1 + r) / (1 + i) - 1, not the subtraction shortcut r - i.

Calculation sequence

  1. Read the current age, retirement age, current balance, the employee and employer contributions, the contribution timing, the salary growth, the return, the inflation assumption, the target income and the withdrawal rate.
  2. Derive the number of years to retirement from the two ages.
  3. Grow the existing balance to retirement at the expected return.
  4. Grow the combined contribution stream using the exact geometric sum for a payment stream rising at the salary growth rate, switching to the limiting form when the growth rate equals the return, and adjusting for whether contributions fall at the start or end of each year.
  5. Add the two to get the projected balance, and deflate it by inflation to express it in today's money.
  6. Apply the withdrawal rate to the projected balance to get the first-year retirement income, and compare it with the target.
  7. Split the balance into contributions paid in and investment growth for the chart.
  8. Evaluate the status in the order given below.

Outputs and interpretation

The headline figures are Projected Balance Today, Projected Balance and First Year Income Today. Everything else is supporting detail for those.

Output Role Unit What it means
Projected Balance Today headline $ The same balance expressed in today's money, which is what tells you what it will buy.
Projected Balance headline $ The balance at retirement, in the money of that year.
First Year Income Today headline $/year The same first-year income in today's money.
Real Return Rate detail percentage Expected return after inflation, computed exactly as (1 + return) / (1 + inflation) - 1. At or below 0%, the balance loses purchasing power.
Years To Retirement detail years Whole years between your current age and your planned retirement age.
Total Contributed detail $ Everything paid in over the period, yours and your employer's, with the salary growth applied. It excludes the balance you started with.
First Year Income detail $/year The income the balance supports in the first year of retirement, at your withdrawal rate, in the money of that year.
Extra Annual Saving detail $/year The additional amount per year that would close the gap by your retirement age. Zero when the target is already met, and blank until you enter a target.
Investment Growth detail $ The projected balance less the opening balance and everything paid in. The year this overtakes contributions is the point compounding takes over.
Income Gap Today detail $/year Target income less projected income, in today's money. Positive means a shortfall. Blank until you enter a target.

Validation and status logic

The workbook evaluates status in this order, and the first condition that is true wins. The status text below is the exact wording the workbook returns; angle brackets mark a value substituted into the message at calculation time.

Condition Returned status
Retirement Age <= Current Age NOT VALID: the planned retirement age must be later than the current age
Withdrawal Rate <= 0 NOT VALID: the withdrawal rate must be above zero
Expected Return < 0 NOT VALID: the expected return cannot be negative
AND(Target Retirement Income <> "",Gap against target, numeric > 0) CHECK: the projection falls short of the target income
Real Return Rate <= 0 CHECK: the expected return does not beat inflation, so the balance loses value in real terms
None of the preceding conditions applies OK

Assumptions and limitations

  • The expected return, salary growth and inflation are constant every year.
  • Returns are smooth, so no volatility or sequence-of-returns risk is represented.
  • Contributions are annual, either at the start or the end of each year, and grow at the salary growth rate.
  • Taxes, fees, contribution limits and employer vesting are outside the model, so the projected balance is a gross figure.

Restrictions and non-computing states

The retirement age must be later than the current age. Contributions and the current balance cannot be negative. The return, salary growth, inflation and withdrawal rate are held within their published ranges. Contribution limits are not applied, so a projection can assume contributions above what a real plan would permit.

Errors and warnings

A rejected entry means a value fell outside the published input rules, and no calculation was attempted. Workbook NOT VALID means the model ran and could not produce a meaningful answer, so the results are withheld. Workbook CHECK means the numbers stand but a condition is worth reading before you rely on them. A connection or calculation-service failure is an availability problem, not a finding of any kind, and never means zero.

References

The compound-interest and growing-annuity relationships are standard financial mathematics and are documented with a worked derivation in the delivered audit. Contribution limits that would cap a real plan are set by the Internal Revenue Service; see 401(k) and profit-sharing plan contribution limits. The workbook does not reproduce a statutory table, and it does not apply those limits to the projection.

This model is arithmetic. It is not financial, tax, investment or retirement advice, and it is not a recommendation to save, invest, withdraw, claim or accept any amount. Decisions about retirement funding should be taken with a qualified professional who knows your circumstances.

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