Retirement Calculator: How Long Will My Money Last?
This calculator projects your 401(k), Roth IRA and taxable brokerage to your retirement date,
then answers the question that actually matters: how long the money lasts once you
stop earning. It runs 500 Monte Carlo simulations rather than a single straight-line
projection, so you get the odds your savings outlive you instead of one falsely precise number.
What makes this different
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500 simulated market histories, not one average. Most "how long will my
money last" calculators apply a fixed return every year. This one varies returns the way
markets actually do, and reports the share of outcomes where your money survives.
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Risk lives in your investments, not your account type. A 401(k) and a
brokerage holding the same index funds grow identically, so the return comes from your
stock/bond mix — Conservative, Moderate or Aggressive — and the simulation draws bond-like
variance on the bond slice and equity-like variance on the equity slice.
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Employer match is counted. For most people it's the single biggest lever
in the plan, and it's a separate contribution stream from your own budget.
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IRS limits are built in. Contribution fields flag when you exceed the
2025 401(k) elective-deferral limit or the IRA cap, and the budget splitter fills
tax-advantaged accounts before taxable ones.
- Free, instant, no signup and no email wall.
Common scenarios
Frequently asked questions
How long will my money last in retirement?
At the classic 4% rule, a portfolio is designed to last roughly 30 years — that's where
the number comes from. But the honest answer is a probability, not a duration: it depends
on what you're invested in, what returns actually arrive and in what order, and how fast
inflation raises your spending. This calculator reports it as the percentage of 500
simulated market histories in which your money survives to your life expectancy.
Can I retire at 62 with $400,000 in my 401(k)?
$400,000 supports about $1,333/month at a 4% withdrawal rate before Social Security.
Retiring at 62 means funding roughly 28 years, which is a long time for that balance to
stretch on its own — but Social Security, which most people claim between 62 and 70, is
an inflation-adjusted income floor on top of it and changes the picture substantially.
See the full simulation for this
scenario.
Who has the most accurate retirement calculator?
No calculator predicts the future, so "accurate" really means honest about uncertainty.
Tools that return one number are the least honest, because they hide the range of
outcomes. Prefer ones that show a distribution — a probability of success and a spread
between good and bad markets — and that let you see and change every assumption behind
the answer.
How much do I need to retire?
The common US rule of thumb is 25× your annual spending, which is the 4% rule stated
backwards. If you spend $60,000 a year, that's $1.5 million. Spending is the input that
matters most — it sets both the target and the withdrawal — which is why this planner
asks for your expenses in the FIRE section rather than assuming a percentage of salary.
Does this include Social Security?
Not yet. Every figure here comes from your own savings, so treat the results as
conservative — Social Security is an inflation-adjusted income floor on top, and for most
households it covers a meaningful share of retirement spending. Estimate yours at
ssa.gov.
What return and inflation assumptions does it use?
Returns come from your allocation: US stocks 10%, international 8.5%, bonds 4.5% and cash
3% nominal, with volatility of 18%, 20%, 6% and 1% respectively. Inflation defaults to 3%
and the withdrawal rate to 4%. All of them are editable — these are long-run averages, not
forecasts, and your results should be read as a range rather than a prediction.
Estimates only, not tax, investment or retirement advice. Results depend entirely on assumptions
that will not match the future exactly. Consult a licensed financial advisor before acting.
