How Long Will My Money Last? Retirement Withdrawal Calculator
See how many years your savings last at a monthly withdrawal, adjusted for inflation, how much you can take for a set number of years, and how it compares with the 4% rule
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How Long Will My Money Last? Retirement Withdrawal Calculator
Printed 2026-10-27 from billorganizingapp.com/income/calculators/how-long-will-my-money-last/ — an estimate for planning, not financial or tax advice.
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Enter what you have saved, what you plan to withdraw each month in today's dollars, and the return and inflation you expect. The calculator shows how long the money lasts, your first-year withdrawal rate, the monthly amount that would last exactly the number of years you choose, and what the 4% rule would give from the same balance. Withdrawals rise with inflation, so the answer is about keeping your spending power, not just a dollar figure.
The formula
The calculator turns your expected return into a real return, (1 + return) ÷ (1 + inflation) − 1, and then into an equivalent monthly rate r = (1 + real return)^(1/12) − 1. With a balance B and a withdrawal W at the end of each month, the money runs out after n = −ln(1 − r × B ÷ W) ÷ ln(1 + r) months. With no growth that is simply B ÷ W. If one month's growth, r × B, is at least W, the balance never shrinks in this steady-return model. The reverse question, how much you can take for n months, is the loan-payment formula: W = B × r ÷ (1 − (1 + r)^−n).
A worked example
With $500,000 saved, $3,000 a month, a 5% expected return and 3% inflation, the real return is 1.94% and the money lasts 16 years 2 months. That is a first-year withdrawal rate of 7.2%. To make the same balance last 30 years at those assumptions you could take about $1,829 a month. The 4% rule would start at $1,667 a month, which at the same steady return lasts 34 years 1 month.
| Monthly withdrawal | First-year rate | Money lasts |
|---|---|---|
| $2,000 | 4.8% | 26 years 7 months |
| $2,500 | 6.0% | 20 years 1 month |
| $3,000 | 7.2% | 16 years 2 months |
| $3,500 | 8.4% | 13 years 6 months |
| $4,000 | 9.6% | 11 years 7 months |
Return assumptions move the answer a lot
A steady return is a simplification. Real markets go up and down, and a fall in the first few years of withdrawals does more damage than the same fall later, because you are selling while prices are low (sequence-of-returns risk). Run a cautious case alongside your central one, as in the table, and keep a cash buffer so you do not have to sell after a fall.
| Return / inflation | Real return | Money lasts | Lasts 30 years at |
|---|---|---|---|
| 3% / 3% | 0.00% | 13 years 10 months | $1,389 |
| 5% / 3% | 1.94% | 16 years 2 months | $1,829 |
| 7% / 3% | 3.88% | 19 years 9 months | $2,334 |
How this compares with the 4% rule
The 4% rule comes from historical studies of US stock and bond returns: William Bengen (1994) and the Trinity study (Cooley, Hubbard and Walz, 1998) found that withdrawing 4% of a portfolio in the first year and raising it with inflation afterwards lasted 30 years in most historical periods they tested for stock-heavy portfolios. It is a finding about the past, not a promise about the future, and it does not tell you how long your own money will last at a different withdrawal. This calculator answers that question with a steady-return assumption; use both as rough guides.
What is not included
Social Security, pensions, annuities and part-time income are not counted: subtract what they pay from your monthly withdrawal before you enter it. Taxes on withdrawals from pre-tax accounts are not modelled, so include them in the withdrawal. Fees reduce your return: take them off the expected return. For a personalised plan, talk to a fee-only fiduciary adviser.
A lump sum or a monthly check
Compare a lottery lump sum with its 30-payment annuity after tax, or the Social Security check at different claiming ages.
Next, read Freelance Runway Calculator.
Official sources
Tax rules, limits and pay data change. Check the current figures with the primary source before acting on them.
Frequently Asked Questions
How do I calculate how long my money will last?+
Convert your expected return to a real (after-inflation) monthly rate r, then months = −ln(1 − r × balance ÷ monthly withdrawal) ÷ ln(1 + r). With no growth it is simply balance ÷ monthly withdrawal: $300,000 at $2,000 a month lasts 150 months, or 12.5 years.
How long will $500,000 last in retirement?+
At $3,000 a month, a 5% return and 3% inflation, about 16 years 2 months in this model. At $2,000 a month it lasts 26 years 7 months. The answer depends mostly on the withdrawal and the return you assume, so try several.
What is the 4% rule?+
A guideline from Bengen (1994) and the Trinity study (1998): withdraw 4% of your portfolio in the first year of retirement and increase that dollar amount with inflation each year. Historically it lasted 30 years in most periods tested for stock-heavy portfolios. It is not a guarantee.
Does the calculator include inflation?+
Yes. Withdrawals are in today's dollars and rise with inflation, and growth uses the real return, (1 + return) ÷ (1 + inflation) − 1.
Why does it say my money lasts indefinitely?+
If one month's real growth on your balance is at least as large as your monthly withdrawal, the balance does not fall in a steady-return model. Real returns vary, so treat it as a sign the withdrawal is modest, not as a guarantee.
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