Run your balance, return, monthly withdrawal, and inflation assumption month by month to see exactly how long the money lasts.
A month-by-month estimate, not a guarantee.
We grow your balance at the expected return each month, subtract that month's withdrawal, then raise the withdrawal slightly for next month based on your inflation rate. The loop repeats until the balance reaches zero. Running it this way, rather than a single closed-form equation, makes it straightforward to see exactly which year the money would run out under your specific numbers.
The 4% rule, used on the retirement calculator and FIRE number calculator, is a shortcut: multiply annual spending by 25 and call that your target, based on research into what has historically survived roughly 30 years. This page skips the shortcut and runs your actual withdrawal amount against your actual return assumption month by month, so it can show a result shorter or longer than 30 years depending on the specific numbers you enter, not a rule of thumb.
| Year | Withdrawn this year | Balance at year end |
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Sizing the starting balance itself first? The retirement calculator projects what you will have going in, and the RMD calculator covers the required minimum distribution rules that apply once you turn 73 on a pre-tax account.
Month by month: the balance grows by your entered return, then the current withdrawal amount is subtracted, then the withdrawal itself grows slightly for the next month based on your inflation assumption. The loop stops the month the balance hits zero, or reports the balance as sustainable past 100 years if it never runs out.
Because withdrawals are rising every year while the return rate stays fixed, inflation quietly increases how much you take out relative to how much the balance earns. A fixed withdrawal with no inflation adjustment always lasts at least as long as the same starting withdrawal that grows every year.
Related but not identical. The 4% rule estimates a starting withdrawal rate meant to last roughly 30 years under historical conditions. This calculator instead runs your specific withdrawal amount, return, and inflation rate month by month to show exactly how long that particular combination lasts, which can be shorter or longer than 30 years depending on your numbers.
No, the return you enter is applied as a smooth constant every month. Real portfolios experience up and down years, and a few bad years early in retirement can deplete a balance faster than this steady-average model shows, a risk known as sequence-of-returns risk that this simplified tool does not capture.
There is no universal answer, but a starting rate somewhere between 3% and 4% of the initial balance is a common range in retirement research for a multi-decade payout. Run this calculator at a few different monthly withdrawal amounts to see how sensitive your specific plan is before settling on one number.