Free Monte Carlo retirement calculator.

How this calculator works

A Monte Carlo retirement projection runs your scenario thousands of times under different random market sequences. Instead of a single projected line that assumes the market behaves perfectly, you get a probability distribution showing the range of outcomes that are actually plausible given the volatility you specified.

This calculator runs 10,000 simulated paths. Each path samples annual returns from a lognormal distribution parameterized by the expected return and volatility you provided. The fan chart above shows the resulting distribution: the band is the 25th-75th percentile and the line through it is the median outcome. The 10th and 90th are in the stat card above and in the hover readout rather than on the chart — a path that reaches zero cannot be placed on a logarithmic scale, so its line stops where the money did instead of being drawn along the axis as though something were left.

Why a single projected line is misleading

Most retirement calculators show a single growing line based on an assumed constant return. That line is essentially never what actually happens. Real markets have great years and terrible years, and the order matters: a 30% drawdown early in retirement is much more damaging than the same drawdown later, even if the long-run average is identical. Monte Carlo captures this sequence-of-returns risk that single-line projections paper over.

The headline probability of success above is the share of those 10,000 paths in which the portfolio still has money at age 95, assuming a 4% annual withdrawal of the median retirement balance. A success rate of 80% means: under your assumptions, four out of five simulated futures end with money still in the account.

What this calculator simplifies

To keep the inputs short, this version treats your savings as a single asset with a single expected return and volatility. It does not model asset allocation glide paths, taxes, Social Security, required minimum distributions, or variable spending. Rikdom's full simulator models each of those; you switch them on and set them in its projection form.

If you want the projection to start from the balances in your real brokerage, 401(k), IRA and HSA accounts, that's what the full Rikdom product does. It also finds the 401(k), IRA and HSA contributions in your account history and keeps them out of “market growth,” so you can see how much of a good year was you. The free calculator here is a separate, simpler model.