I built FireMathLab around one idea: a retirement plan is a range of outcomes, not a promise. Markets don't move in straight lines, so a single projected retirement age never tells the whole story. Every tool on the site starts from that. The Monte Carlo simulator runs your numbers through 1,000 randomised market paths. The backtest replays them through 124 years of real market history, including the stretches that would have wrecked you. The crash test drops a 35% crash on the day you retire and checks whether the plan survives. And Rich, Broke or Dead puts life expectancy on the same chart as your portfolio, which changes how the whole question feels. A few principles I held onto the whole way: every tool works without an account, nothing ever connects to your bank, all 30+ calculators are free, and every formula is public on the methodology page. If you want to check my maths, you can. And if you want to keep your numbers, a free account saves your plans and brings them back next visit. It's early days and I'd genuinely value rough feedback. If a number looks wrong, tell me and I'll trace it through the engine. Ask me anything.

firemathlab

Math simplified

Math simplified