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finance-business · personal-finance · retirement-income

Retirement Drawdown Withdrawal Calculator

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.

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Calculator overview

Inputs and outputs

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

Inputs

Current Age (required)
About this input

Your age when drawing begins. Used only to label the chart and to report the age at which the balance would fall short.

Unit years Default 65 Range 18 to 80
Expected Return (required)
About this input

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

Unit fraction Default 0.05 Range 0 to 0.25
First Year Withdrawal (required)
About this input

What you plan to take in the first year. Later years rise with inflation so the purchasing power stays level.

Unit currency/yr Default 40000 Range At least 0
Inflation Rate (required)
About this input

The average annual inflation you expect, expressed as a percentage. It raises the withdrawal each year and converts the ending balance into today's money.

Unit fraction Default 0.025 Range 0 to 0.15
Life Expectancy Factor
When omitted Blank
About this input

Optional. The life-expectancy divisor from the published minimum-distribution table for your age. Leave it blank and the two RMD outputs stay blank; supply it and the calculator reports the first-year minimum and whether it forces a larger withdrawal than you planned.

Unit years Default Not set Range 1 to 120
Retirement Years (required)
About this input

How many years the money has to last. It is a planning horizon, not a prediction of lifespan.

Unit years Default 30 Range 1 to 60
Starting Balance (required)
About this input

What the retirement accounts hold on the day drawing begins, across all of them.

Unit currency Default 1000000 Range At least 0

Outputs

Depletion Age
About this output

Your age in that year. Zero when the balance lasts the whole period.

Unit years
Depletion Year
About this output

The first year in which the full inflation-adjusted withdrawal could not be met. Zero means it never happened within the period.

Unit years
Ending Balance
About this output

What remains at the end of the period, in the money of that year. Zero means the balance was exhausted.

Unit currency
Ending Balance Today
About this output

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

Unit currency
Headroom Versus Plan
About this output

The sustainable withdrawal less the one you planned. Positive means you could take more; negative means the plan is drawing faster than the balance supports.

Unit currency/yr
Initial Withdrawal Rate
About this output

The first-year withdrawal as a share of the starting balance. Four percent is the conventional reference point, not a rule.

Unit fraction
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
Real Return Rate
About this output

The expected return after inflation, computed exactly as (1 + return) / (1 + inflation) - 1. It is what decides whether a balance can sustain a withdrawal indefinitely.

Unit fraction
Required Minimum First Year
About this output

The first-year required minimum distribution: the balance divided by the life-expectancy factor. Blank until you supply a factor.

Unit currency/yr
RMD Exceeds Plan
About this output

Whether that minimum is larger than the withdrawal you planned, in which case the minimum is what you would actually have to take. Blank until you supply a factor.

No unit declared
Sustainable Withdrawal
About this output

The first-year withdrawal that would leave the balance at exactly zero at the end of the period, rising with inflation throughout.

Unit currency/yr
Total Withdrawn
About this output

Everything taken out across the period, in nominal money, which is why it exceeds the starting balance when the plan works.

Unit currency
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.

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Methodology

Purpose and model boundary

Use this calculator to test a level-of-purchasing-power retirement withdrawal against a starting balance, return assumption, inflation and planning period. It reports whether the balance lasts, when it would run short, the ending balance in today's money, and the constant withdrawal the assumptions can support.

The projection uses one smooth annual return. It excludes volatility and sequence-of-returns risk, taxes, fees, changing spending, annuity purchases and retirement income not entered in the calculator.

Inputs and units

Input Unit Accepted range What it means
Life Expectancy Factor years 1 to 120 Optional. The life-expectancy divisor from the published minimum-distribution table for your age. Leave it blank and the two RMD outputs stay blank; supply it and the calculator reports the first-year minimum and whether it forces a larger withdrawal than you planned.
Retirement Years years 1 to 60 How many years the money has to last. It is a planning horizon, not a prediction of lifespan.
Starting Balance $ 0 or more What the retirement accounts hold on the day drawing begins, across all of them.
Inflation Rate percentage 0–15% The average annual inflation you expect. It raises the withdrawal each year and converts the ending balance into today's money.
Current Age years 18 to 80 Your age when drawing begins. Used only to label the chart and to report the age at which the balance would fall short.
Expected Return percentage 0–25% The average annual return you expect on the remaining balance, after fees and before inflation.
First Year Withdrawal $/year 0 or more What you plan to take in the first year. Later years rise with inflation so the purchasing power stays level.

Governing relationships

The calculator first converts nominal return and inflation to real return: (1 + nominal) / (1 + inflation) - 1. With real return g and withdrawal W, the balance follows B(k+1) = (B(k) - W)(1 + g). After n years that becomes (1 + g)^n B - W (1 + g) [(1 + g)^n - 1] / g. The sustainable withdrawal is the annuity-due payment B g / (1 - (1 + g)^-n) / (1 + g), with a separate zero-return branch.

Calculation sequence

  1. Read the starting balance, current age, the number of retirement years, the first-year withdrawal, the return and inflation assumptions and any life-expectancy factor.
  2. Convert the nominal return and inflation into a single real return using the exact Fisher relation.
  3. Compute the sustainable first-year withdrawal as the annuity-due payment on the real return over the period.
  4. Roll the balance forward year by year, taking the withdrawal at the start of each year and growing the remainder at the real return.
  5. Record the first year in which the balance falls short, if any, and the ending balance in today's money.
  6. Where a life-expectancy factor is given, derive the required minimum distribution for comparison against the planned withdrawal.
  7. Sweep the withdrawal rate to produce the ending balance across a range of first-year withdrawals for the chart.
  8. Evaluate the status in the order given below.

Outputs and interpretation

The headline figures are Sustainable Withdrawal, Depletion Year and Ending Balance Today. Everything else is supporting detail for those.

Output Role Unit What it means
Sustainable Withdrawal headline $/year The first-year withdrawal that would leave the balance at exactly zero at the end of the period, rising with inflation throughout.
Depletion Year headline years The first year in which the full inflation-adjusted withdrawal could not be met. Zero means it never happened within the period.
Ending Balance Today headline $ The same ending balance in today's money, which is what tells you what it would buy.
Required Minimum First Year detail $/year The first-year required minimum distribution: the balance divided by the life-expectancy factor. Blank until you supply a factor.
Real Return Rate detail percentage Expected return after inflation, computed exactly as (1 + return) / (1 + inflation) - 1. It helps explain how quickly purchasing power changes.
Total Withdrawn detail $ Everything taken out across the period, in nominal money, which is why it exceeds the starting balance when the plan works.
RMD Exceeds Plan detail Whether that minimum is larger than the withdrawal you planned, in which case the minimum is what you would actually have to take. Blank until you supply a factor.
Ending Balance detail $ What remains at the end of the period, in the money of that year. Zero means the balance was exhausted.
Depletion Age detail years Your age in that year. Zero when the balance lasts the whole period.
Initial Withdrawal Rate detail percentage First-year withdrawal as a percentage of the starting balance. Four percent is a common reference point, not a rule.
Headroom Versus Plan detail $/year The sustainable withdrawal less the one you planned. Positive means you could take more; negative means the plan is drawing faster than the balance supports.

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
Starting Balance <= 0 NOT VALID: there is no balance to draw from
Retirement Years <= 0 NOT VALID: the money has to last at least one year
First Year Withdrawal < 0 NOT VALID: the withdrawal cannot be negative
Expected Return < 0 NOT VALID: the expected return cannot be negative
Depletion Year > 0 CHECK: the balance runs short in year <depletion year>, before the end of the period
First Year Withdrawal > Sustainable Withdrawal CHECK: the planned withdrawal is above the sustainable figure for this period
RMD, numeric > First Year Withdrawal CHECK: the required minimum distribution is larger than the planned withdrawal
None of the preceding conditions applies OK

Where a message substitutes a value, these are the exact returns the delivered corpus records:

  • CHECK: the balance runs short in year 38, before the end of the period
  • CHECK: the balance runs short in year 14, before the end of the period
  • CHECK: the balance runs short in year 20, before the end of the period

Assumptions and limitations

  • Returns are constant and smooth. There is no volatility, so sequence-of-returns risk, the single largest danger to a drawdown plan, is not represented.
  • Withdrawals are taken at the start of each year and rise with inflation, so the figures are in today's money.
  • Taxes, platform and fund fees, and any change in spending pattern are outside the model.
  • The life-expectancy factor is an input used only for comparison against a required minimum distribution. It is not a mortality projection.

Restrictions and non-computing states

The starting balance must be greater than zero and the period at least one year. The withdrawal and the expected return cannot be negative. Inflation, the withdrawal amount and the life-expectancy factor are held within their published ranges. A balance that runs short does not stop the calculation: the schedule continues and the year of depletion is reported, because the year it happens is the useful answer.

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 balance recursion and annuity-due relationships are standard financial mathematics and are documented with a worked derivation in the delivered audit. Where the projection is compared against a required minimum distribution, the governing rules are the Internal Revenue Service's; see the required minimum distributions FAQs. The workbook does not reproduce a statutory table.

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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