How Long Will My Money Last Calculator
$500,000 withdrawing $25,000 a year at 5% return lasts about 30+ years — enter your numbers below for your exact figure.
Math illustration only — not financial advice. Actual returns, inflation and taxes vary.
How the money-last calculator works
The calculator runs a month-by-month simulation: each month your balance grows by one-twelfth of the annual return, then that month’s withdrawal is subtracted. The monthly withdrawal is the annual amount divided by 12, grown by inflation each month so it keeps buying the same lifestyle, and any other annual income — a pension or Social Security — is subtracted from the withdrawal first. The simulation stops when the balance hits zero, or at 720 months (60 years).
Inflation matters more than most people expect: 3% annual inflation halves purchasing power in about 24 years, so a flat withdrawal that covers your lifestyle today covers only half of it in 24 years. That is why this calculator grows withdrawals with inflation instead of holding them flat — it answers how long the same standard of living lasts, not just how long a fixed dollar amount lasts.
balance(m+1) = balance(m) × (1 + r/12) − max(0, W/12 − O/12) × (1 + inf/12)^m
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Use the 401k vs Roth 401k Calculator to grow the savings you are measuring here, or compare keeping the money invested against the CD Ladder Calculator for a lower-risk income stream.
How long will my money last calculator FAQ
What is the 4% rule?
Withdraw 4% of the portfolio in year one, then adjust that amount for inflation each year; designed to fund roughly 30 years (Bengen, 1994).
Does inflation really matter that much?
Yes: 3% annual inflation halves purchasing power in about 24 years, so withdrawals must grow to buy the same lifestyle.
What if my return is 0%?
Then money lasts savings ÷ annual withdrawal years, ignoring inflation; e.g. $500,000 ÷ $25,000 = 20 years.
How long will $500,000 last withdrawing $20,000 a year?
About 25 years at 0% return; longer with investment growth — the calculator above runs your exact numbers.
Should I count Social Security or a pension?
Yes — enter it as other annual income; it directly reduces what your portfolio must cover.