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Monte Carlo Retirement Calculator: How Long Will Your Money Last?

See how long your retirement savings last across real S&P 500, bond and inflation years since 1928, plus every historical retirement period.

How long will your money last?

Chance your money lasts

90%

9,049 of 10,000 simulated retirements

Median balance after 30 years of retirement

$1,611,585

In today's dollars

In the simulations where the money ran out, the median year it ran out was year 25.

Ending balance by percentile, in today's dollars
Ending balanceToday's dollars
10th percentile$30,512
25th percentile$597,034
Median$1,611,585
75th percentile$3,210,207
90th percentile$5,355,895

The same plan lasted in 65 of 69 real 30-year retirements starting 1928–1996; it ran out when starting in 1965, 1966, 1968, 1969.

Source: Damodaran (NYU Stern) and FRED. Data through 2025. How the simulation works

The order of returns matters

The same plan started in three real years, in today's dollars.

  • Start in 1929: $523,731 left at the end
  • Start in 1966: ran out in year 26
  • Start in 1982: $5,360,383 left at the end

Will your savings last? Test the plan against real history

This calculator replays real S&P 500, 10-year Treasury and inflation figures from 1928 to 2025. Enter your savings, spending and stock share, and it shows how often the money lasts, both across 10,000 simulated retirements and across every real retirement start year. The default is the classic 4% rule: $1,000,000 saved, $40,000 a year of spending, 30 years, 60% stocks.

How this simulation works

Each simulated year is one real year picked at random from 1928 to 2025. The stock return, bond return and inflation of that year are used together, so a bad stock year keeps its inflation with it. There is no assumed average return and no assumed volatility. Each plan runs 10,000 times. The historical-periods check is the non-random version: it starts the same plan in every real year that leaves room for the full horizon and counts how many times the money lasted.

Limits

  • US data only. The US market did better than most, so other countries may have fared worse.
  • One step per year. Moves inside a year are not modeled.
  • Years are drawn independently, so the simulation does not repeat long runs like the 1930s or the 1970s. The historical-periods check does.
  • No taxes, Social Security, pensions or other income. The only fee is the one you enter. Spending rises with inflation every year and does not adjust to market results.

Sources and method: methodology. For the idea behind it, read Monte Carlo simulation for retirement planning.

Related guides

Built and maintained by Oscar Gallego Ruiz. Historical data through 2025. Methodology and sources.

Disclaimer: WealthSim is an independent educational tool for financial simulation and is not affiliated with any financial institution, including Wealthsimple. All calculations are for educational purposes and do not constitute financial advice.

Frequently Asked Questions

Does the 4% rule still work?
For $1,000,000 saved, $40,000 a year of spending raised with inflation, 30 years and 60% stocks, the money lasted in 90% of 10,000 simulated retirements built from real years since 1928. Replaying every real 30-year period, it lasted in 65 of 69. The periods that failed started in 1965, 1966, 1968, 1969. Both figures use US stocks and 10-year Treasuries only, with no taxes or fees, so treat them as a guide and not a promise.
What is a Monte Carlo retirement simulation?
It runs the same plan many times with different sequences of market returns and counts how often the money lasts. This calculator runs 10,000 retirements. The share that never ran out of money is the probability of success. The result is a probability, not a forecast.
Why use real historical years instead of an average return?
An average hides the order of returns, and the order decides whether withdrawals dig a hole early. Here every simulated year is one real year from 1928 to 2025, so its stock return, bond return and inflation stay together. There is no assumed average return or volatility to get wrong.
What is sequence of returns risk?
It is the risk that bad returns arrive early in retirement, when withdrawals are largest relative to the portfolio. With the same plan, starting in 1966 the money ran out in year 26, while starting in 1982 $5,360,383 was left after 30 years (in today's dollars). The average return over the period matters less than when the bad years fall.
What does this calculator leave out?
Taxes, Social Security, pensions, other income, and any change in spending after a market drop. It uses US data only and takes one step per year. Years are drawn independently in the simulation, so it does not repeat long bear markets; the historical-periods count does. It is an educational tool, not financial advice.

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