Financial Independence Simulator

Your FIRE number is the portfolio size at which investment returns can cover your spending indefinitely. The classic 4% rule divides annual spending by a safe withdrawal rate: $48,000 of annual spending at a 4% withdrawal rate gives a $1.2 million target. This simulator applies whatever withdrawal rate you choose (3–5% is the usual range; lower is more conservative).

Each simulated run draws a different sequence of annual returns from a distribution with your expected real return and volatility. The success rate is the share of runs in which your portfolio reaches the FIRE number by your planned retirement age. A 90%+ rate is traditionally considered very safe; 70–90% is common for flexible early-retirement plans.

The deterministic projection compounds your average return every year, while the Monte Carlo median reflects the full distribution — in a lognormal-ish world, bad-sequence years drag on some paths, so medians can sit slightly below the smooth line. The band (10th–90th percentile) shows the realistic spread around both.

No. This is an educational model with simplifying assumptions: contributions stay constant in real terms, returns are independent each year, taxes and Social Security are ignored, and spending is assumed flat in retirement. Use it to build intuition and compare scenarios, then validate big decisions with a qualified fiduciary planner.

No. Every simulation runs locally in JavaScript — your numbers are never uploaded, stored, or tied to an account, unlike paid planning platforms that gate this same math behind $100+/year subscriptions.