How Long Will My Money Last?

Enter your savings balance, how much you withdraw each month, and the return you expect in retirement. You'll get how long the money lasts in years and months — or a note that it lasts indefinitely — plus balances at 5-year checkpoints.

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How this calculator works

It runs your retirement month by month: each month your balance earns one month of investment return, then your withdrawal comes out. If you enter an inflation rate, the withdrawal gets a raise every 12 months — because the $2,500 that covers your bills today won't cover them in 2040. The answer is the moment the balance hits zero, or a happy notice that it never does.

That second outcome is real: if your balance earns more each month than you take out, the portfolio grows forever and the honest answer isn't a number of years — it's "indefinitely."

The formula

balancenext = balance × (1 + r) − withdrawal,  where r = (1 + R)1/12 − 1

R is your annual return as a decimal and r is its monthly equivalent. The withdrawal is multiplied by (1 + inflation) at the end of each year. There's no closed-form answer once inflation is involved, which is exactly why this is a simulation and not a one-line formula.

Worked example

$500,000 saved, withdrawing $2,500/month, earning 5% a year, with withdrawals rising 3% a year for inflation:

The money lasts about 20 years, 7 months. After 5 years you'd still have about $458,643; after 10 years, $377,270; after 15, $240,273 — the decline accelerates as withdrawals grow and the balance shrinks. Ignore inflation and the same money appears to last 34 years, 7 months. That 14-year gap is why the inflation field matters.

The 4% rule — and its fine print

The classic guideline says: withdraw 4% of your starting balance in year one, raise it with inflation each year, and a diversified portfolio has historically survived 30 years. It's a genuinely useful starting point — on $500,000 that's about $1,667/month. But it came from backtests of US markets in the 20th century, assumed a roughly 50/50 stock/bond mix, and ignores taxes and fees. Some researchers now argue for 3.3%; others say 4.5%+ is fine if you can cut spending in bad years. Treat it as a sanity check, not a guarantee.

One risk this calculator can't show: sequence-of-returns risk. We assume a smooth, identical return every year, but real markets deliver lumpy ones — and two retirees with the same average return can get wildly different outcomes depending on the order. A crash in your first years of withdrawals forces you to sell more shares at low prices, permanently shrinking the base that later recoveries compound on. It's why retiring into a bear market is more dangerous than living through one mid-retirement, and why many planners keep 1–2 years of spending in cash.

Frequently asked questions

How long will $500,000 last in retirement?

It depends almost entirely on your withdrawal rate and returns. Withdrawing $2,500/month with a 5% return and 3% inflation, $500,000 lasts about 20 years and 7 months. Drop the withdrawal to about $1,700/month and it can last 30+ years. Run your own numbers above — small changes in the monthly amount move the answer by years.

What is the 4% rule?

A guideline from historical backtests: withdraw 4% of your starting balance in the first year, increase the dollar amount with inflation annually, and a diversified portfolio has usually lasted at least 30 years. It assumes a roughly half-stock portfolio and ignores taxes and fees, so treat it as a starting point rather than a promise.

What investment return should I assume in retirement?

Most retirees shift toward bonds, so assuming 4-6% is more realistic than the 8-10% often quoted for all-stock portfolios. Being conservative here is cheap insurance: if you plan around 4% and earn 6%, the surprise is pleasant rather than catastrophic.

Does this calculator account for inflation?

Yes, optionally. Enter an inflation rate and your monthly withdrawal automatically grows by that percentage each year, which models keeping your purchasing power constant. Leaving it blank assumes you withdraw the same dollar amount forever, which understates what you'll actually need.

What is sequence-of-returns risk?

The risk that bad market years arrive early in retirement, when your balance is largest and withdrawals force you to sell at low prices. Two retirees with identical average returns can end up in very different places depending on the order of good and bad years. This calculator assumes a steady return, so treat its answer as a midpoint, not a floor.

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