Retirement Stress Test – Monte Carlo Retirement Calculator

Retirement Stress Test

Will the money last? A Monte Carlo test of stocks, bonds, Social Security and pension. All figures are in today’s dollars, and the starting values are an example, not your numbers.

Educational tool only. Results are hypothetical and come from simulations using the assumptions you enter. They do not reflect actual investment results and are not forecasts or guarantees of future results. Actual results may be better or worse and may vary over time. This tool does not provide financial, tax, or investment advice. Talk to a qualified professional before making decisions.

Your numbers

Privacy: The calculator processes the numbers you enter in your browser. We do not send or collect those numbers. Your entries may be saved locally in your browser so they are available when you return.

Household

Your age

Spouse age

Retire at

Plan through age

Set spouse age to 0 to plan for one person.

Portfolio

Current balance ($)

Saving per year until retire ($)

Stock / bond mix today: 60 / 40

Stocks after retiring (%)

Tax on withdrawals (%)

The mix shifts in a straight line from today’s to the retirement mix, and is rebalanced yearly.

Market assumptions (per year, before inflation)

Stock return (%)

Stock volatility (%)

Bond return (%)

Inflation (%)

Advanced

Bond volatility (%)

Stock-bond correlation

Simulations

Volatility is how much returns bounce around from year to year. Correlation is how much stocks and bonds move together. More simulations give a steadier percentage. Running new random paths changes the result slightly each time. The defaults are fine for most people.

Retirement income (today’s dollars per year)

Your Social Security ($)

Starting at age

Spouse Social Security ($)

Spouse starts at age

Pension ($)

Pension COLA (%)

The pension starts at retirement. With 0% COLA its buying power erodes with inflation. Social Security keeps pace with inflation.

Spending

Spending per year, after tax ($)

Share of simulated paths where the money lasts

Median at end

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Bad case (10th pct) at end

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Median at retirement

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First-year withdrawal

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Withdrawal rate

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Median age if it runs out

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Portfolio value by age

Today’s dollars. Hover or tap the chart to read values.

10th to 90th percentile 25th to 75th Median

Milestones

Portfolio percentiles and share of paths still funded.

Age	10th	25th	Median	75th	90th	Still funded

How it works: Each year, stocks and bonds draw correlated random returns, returns are adjusted for inflation, and the portfolio is rebalanced. Before retirement, your savings are added. After retirement, spending minus Social Security and pension is withdrawn, with withdrawals increased to account for taxes. A path fails the first year the balance can’t cover the required withdrawal. This is a simplified model and does not capture every market behavior. Returns follow a normal distribution, which understates the extreme swings (“fat tails”) of real markets. Inflation is fixed, and spending is never cut in bad years. Because the simulations use random paths, results may vary each time you run the tool. Treat the results as a rough guide, not a forecast. This is an educational tool, not financial advice.