Retirement Drawdown Calculator: How Long Will Your Money Last?

What a retirement drawdown calculator can answer

A retirement drawdown calculator answers a different question from a FIRE number calculator. Instead of asking how much you need to accumulate, it starts with the portfolio you have and tests the years after withdrawals begin. The result makes the trade-off between spending, income, return, and inflation visible in one place.

The estimate is most useful as a range. A balance that lasts 32 years in a base case may last fewer years when returns arrive in a poor sequence or healthcare costs rise. Run a lower-return and higher-spending scenario before treating the displayed age as a decision.

How the annual balance projection works

Each year begins with the prior ending balance. The model applies the expected annual return, then subtracts the spending gap: annual spending minus other income. Spending and other income are both increased by the inflation assumption for the next year. If income covers spending, the withdrawal is zero and the portfolio can continue to grow in this simplified model.

The schedule stops when the ending balance is zero or below. A 100-year cap keeps the tool usable for scenarios that never deplete, while the result card makes that cap clear. This is an arithmetic projection, not a historical backtest or a Monte Carlo simulation.

Scenarios worth comparing

Start with a base case that uses your current spending and a documented return assumption. Then test a stress case with lower returns, higher inflation, or a larger spending gap. A flexibility case can include part-time income or a temporary spending reduction, but only if that income or change is realistic for your household.

You can also compare the result with a safe withdrawal rate calculation. The withdrawal rate is the first-year spending gap divided by the portfolio; the drawdown schedule shows what happens year by year when that gap changes with inflation. Looking at both prevents one percentage from hiding a long planning horizon.

Important limits before relying on the result

The model does not know whether your return is nominal or real, so enter a nominal return when you also enter inflation. It does not calculate personal taxes, account access, required distributions, insurance premiums, housing changes, or fees. Keep those items in a separate budget and adjust the spending input when they are expected to change.

For a high-stakes retirement decision, verify benefit start dates and account rules with current official information. The IRS retirement-plan guidance linked below is a starting reference, not individualized tax advice. Save dated scenarios so you can compare assumptions with actual portfolio and spending changes.

How to use the result in a retirement plan

Run a base case using the spending you can explain from a recent budget, then save the assumptions and date. A second case should change only one major variable, such as the expected return or the age when withdrawals begin. Keeping the other inputs steady makes the effect of that choice easier to understand than changing everything at once.

Use the annual schedule to find the years that deserve a closer look. If the balance drops quickly early in the projection, test a smaller first-year withdrawal or a realistic income source. If the balance grows for many years, test higher healthcare or housing costs instead of treating the ending balance as spare money. Revisit the calculation when your spending, benefits, tax rules, or portfolio mix changes.

When to test a second method

This calculator uses a deterministic annual return, so it is easy to inspect but cannot show the full range of possible market paths. A cash-flow spreadsheet can add irregular expenses, taxes, and account order. A Monte Carlo model can show a distribution of outcomes, but its result still depends on the return and volatility assumptions you choose.

Use a second method when the decision is close to a boundary, such as retiring soon or relying on a portfolio that may run out in a few years. The purpose is not to find one perfect number. It is to see whether your plan remains workable after reasonable changes to returns, inflation, spending, and income.

Keep the methods comparable: use the same starting balance, spending gap, inflation assumption, and benefit timing before comparing results. Differences caused by inputs are more useful than a false sense of precision from two models that describe different households.

Pair the displayed depletion age with a cash reserve, insurance review, and a plan for flexible spending. A scenario becomes more useful when it is connected to actions you can revisit, rather than treated as a pass-or-fail forecast.