Will your money last through retirement? Enter your numbers below and run hundreds of market simulations to see your probability of success — free, no signup.
Traditional retirement calculators assume a fixed return every year. Reality is messier. Monte Carlo simulations model that messiness to give you a realistic picture.
Each simulation generates random annual returns from a parametric Gaussian around the expected return you enter. Some years gain, others lose. The calculator models this variability across 100–1,000 scenarios. Hypothetical only — not advice.
View the 10th, 50th (median), and 90th percentile final values. Understand your worst case, typical, and best case scenarios at a glance.
See what percentage of simulations ended with money remaining. 90% means 9 out of 10 market scenarios supported your withdrawal plan through retirement.
A fixed 7% return assumption ignores the reality that returns vary wildly year to year. Monte Carlo shows you what could happen, not just what might happen on average.
Markets don't return 7% every year. Some years surge, others crash. Monte Carlo captures this randomness using Gaussian distribution.
See how your retirement holds up in the worst 10% of scenarios, not just the median. Plan for adversity, not just average outcomes.
Change your withdrawal rate, starting balance, or timeline and re-run the simulation instantly. See how small changes affect your success rate.
A Monte Carlo simulation runs 100–1,000 retirement scenarios with randomized returns. Instead of assuming a fixed 7% every year, it draws returns from a parametric distribution around the expected return you enter. The result is a probability of success rather than a single projection. Hypothetical — not advice.
This widget runs 100 to 1,000 iterations. Each iteration generates random annual returns around the expected return and volatility you enter, using a Box-Muller transform for a Gaussian distribution. You can see the 10th, 50th, and 90th percentile outcomes. The full projector uses the same parametric approach on your named plan’s cash flows.
The probability of success shows what percentage of simulations ended with money remaining at your target date. For example, 90% success means that in 90 out of 100 simulated market scenarios, your portfolio lasted through retirement. Most planners consider 80-90% success rates acceptable.
Yes, completely free with no account required. Enter your portfolio, spending, and timeline above and run the simulation instantly. Your data stays in your browser, and you can use the full projector for more detailed analysis.
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Try it nowThis page is a quick widget. The full app starts blank, walks you through Own → Save → Goal (or Skip), and lets you save named plans, toggle Today's dollars / Future dollars, and back up or share a plan. Hypothetical only — not advice. Not a full replacement for paid planners.
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