Early Retirement MathFIRE Calculators
FIRE Calculator Suite

Safe Withdrawal Rate Analyzer

Can your portfolio survive 30, 40, or 50 years of withdrawals? Run Monte Carlo simulations to stress-test your withdrawal rate across thousands of randomized market scenarios and see the probability of success.

Total invested assets at retirement
How much you withdraw each year (adjusted for inflation)
How many years your portfolio needs to last
Stock/bond mix determines return and volatility

Survival Rate

94.9%

949 of 1,000 simulations survived 30 years

Withdrawal Rate
4.0%
Median Ending Balance
$3,928,904
Worst Case (10th %ile)
$575,566
Median Depletion Year
Year 26

Portfolio Projection

How it works

Methodology

This calculator uses Monte Carlo simulation to model your retirement portfolio. Each simulation generates random annual returns based on the mean and standard deviation of your chosen asset allocation, applies your inflation-adjusted withdrawal, and tracks the balance year by year. The process repeats for the number of simulations you specify (default 1,000) to produce a distribution of outcomes.

The Percentiles chart shows a cone of possible outcomes: the shaded areas represent the 75th and 90th percentile bands, the solid line is the median (50th percentile), and the dashed line is the 10th percentile — the worst-case scenario in which 90% of simulations performed better. If the 10th percentile stays above zero, your withdrawal rate is very robust.

The Paths chart displays 50 individual simulation runs, colored green if the portfolio survived the full time horizon and red if it was depleted. This gives you an intuitive feel for the range of possible outcomes. The By Rate chart compares survival rates across five common withdrawal rates so you can find the right balance between spending and safety.

All calculations run entirely in your browser. No data is sent to any server.

Common questions

FAQ

What is a safe withdrawal rate?

A safe withdrawal rate (SWR) is the percentage of your portfolio you can withdraw each year in retirement without running out of money. The most well-known benchmark is the '4% rule,' which originated from the 1998 Trinity Study. It found that a 4% initial withdrawal, adjusted annually for inflation, survived 30 years in most historical periods. For early retirees with 40-60 year horizons, researchers recommend a more conservative 3.25%-3.5% rate.

What is Monte Carlo simulation?

Monte Carlo simulation is a statistical technique that runs a scenario thousands of times using randomly generated returns drawn from a probability distribution. Instead of relying on a single historical sequence, it produces a range of outcomes and a probability of success. This gives you a much more robust picture of how your portfolio might perform across different market conditions.

Is the 4% rule still valid?

For a traditional 30-year retirement, the 4% rule remains a reasonable starting point based on historical U.S. market data. However, for early retirees planning 40-60 year retirements, the 4% rule may be too aggressive. Lower bond yields and higher equity valuations in recent decades have led researchers to suggest 3.25%-3.5% for longer time horizons. Use this calculator to see how different rates perform over your specific time horizon.

How does inflation affect withdrawals?

In this model, your annual withdrawal is adjusted upward each year by the inflation rate you specify. This means you maintain the same purchasing power throughout retirement, but the dollar amount you withdraw grows over time. Higher inflation rates increase the total amount withdrawn and reduce the probability of your portfolio surviving the full time horizon.

What are the limitations of this calculator?

This calculator uses normally distributed random returns, which may underestimate the frequency of extreme market events (fat tails). It does not account for taxes, Social Security, pensions, or dynamic withdrawal strategies (such as reducing spending in down markets). It also assumes a fixed asset allocation throughout retirement. For a complete retirement plan, combine these results with tax planning and income floor analysis.

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