How this calculator works
The payout uses the loan payment formula in reverse: the balance is the “loan” you pay yourself back over the period, while the remainder keeps earning.
The rate is the return the money earns while you draw it down, converted to a monthly rate.
In “how long it lasts” mode, the number of months is solved from the same formula. If your withdrawals are smaller than the growth, the money never runs out.
This models a self-managed drawdown or a fixed-period annuity, not a life annuity bought from an insurer, whose payout also depends on your age.
Worked example
$500,000 paid out over 25 years at 4.5%
- Monthly payout: about $2,754.
- Total paid: about $826,000.
- About $326,000 of that comes from growth along the way.
Questions people ask
What is a life annuity?
An insurance product that pays for life, however long you live, in exchange for a lump sum. Payout rates depend on age, sex and interest rates.
Is a fixed withdrawal safe in a falling market?
Withdrawing a fixed amount after losses can drain savings faster. Many retirees reduce withdrawals in bad years.
Should I include taxes?
Withdrawals from traditional IRAs and 401(k)s are taxed as income, so the spendable amount is lower. Roth withdrawals are usually tax-free.
How is this different from the 4% rule?
The 4% rule aims to last about 30 years with inflation increases; this calculator spends the balance to zero over the exact period you choose.
Last reviewed October 2, 2026