Retirement Withdrawal Calculator

How to read your result

How long the money lasts is a tug-of-war between two forces: your withdrawal pulls the balance down each period, while the return earned on what remains pushes it back up. When the return is larger, the balance holds or grows and the calculator reports "Indefinite on these assumptions" rather than a fabricated year — when the withdrawal is larger, the decline accelerates as the shrinking balance earns less and less. Compare the current withdrawal rate against the widely cited 4% reference point, and check the break-even return the calculator reports: that's the return your plan would need to roughly preserve the balance rather than draw it down. Switch between fixed, inflation-adjusted, and percentage-of-balance withdrawals to see the real trade-off between steady income, steady purchasing power, and never running out.

Formula used for portfolio drawdown

The projection runs the drawdown month by month, so withdrawal increases, frequency, fees, taxes, and timing are all applied across the schedule. The assumptions you enter are shown in full on the page and in the downloadable model.

Worked example — month 1 by hand

Take the calculator's default plan: a $600,000 balance, a $3,000 monthly withdrawal, a 5% annual return, and 3% inflation, with end-of-month timing. The monthly return factor is 0.05 ÷ 12 ≈ 0.004167, so month 1 credits 600,000 × 0.004167 ≈ $2,500 of growth, lifting the balance to $602,500. The $3,000 withdrawal then leaves $599,500 after month 1.

Because the withdrawal exceeds the interest by about $500, the balance falls each month — and as it shrinks, the interest it earns falls too, so the decline accelerates. Running the same step month by month, the engine projects the money lasting about 35 years 11 months on these defaults. Switching to inflation-adjusted withdrawals steps the amount up by 3% each year (to $3,090 in year 2), which preserves purchasing power but drains the portfolio far sooner — about 20 years 10 months.

Assumptions

• The drawdown runs month by month; the remaining balance earns a single constant periodic return (annual return ÷ periods per year, after fees), then the withdrawal is taken (or the reverse, depending on your timing setting).
• Current withdrawal rate = first-year withdrawals ÷ starting balance — the headline gauge for sustainability, with about 4% as a common reference point.
• Inflation-adjusted value discounts a future withdrawal to today’s purchasing power: real value = withdrawal ÷ (1 + inflation)ʸ.
• A plan whose return covers its withdrawals does not deplete in this constant-return model and is shown as “Indefinite on these assumptions” rather than a fabricated year.
• Optional tax is a simplified flat rate applied to withdrawals; the gross amount still leaves the portfolio.

Limitations

This tool estimates the drawdown math under a constant return. It does not model:

• Sequence-of-returns risk and real market volatility (the model uses a constant return)
• Country-specific tax rules on pensions, withdrawals, dividends, or capital gains
• Required minimum distributions, pension access ages, and contribution rules
• Guaranteed income products such as annuities
• Social Security, the State Pension, or other outside income streams

Frequently asked questions

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Read the guide

For how a withdrawal projection is actually built, and why the "years your money lasts" figure shifts so much when you nudge one input, see How to Estimate Retirement Withdrawals Without Overtrusting One Number.