Your FIRE number is the amount you need invested so that a safe withdrawal covers your spending for life. The common shortcut is 25 times your yearly retirement spending, which comes from the 4% rule: withdrawing about 4% of your portfolio each year has historically lasted 30 or more years across most market conditions.

The chart above compounds your current savings and monthly contributions at a real return, after inflation, so every figure is shown in today's dollars. That matters, because a target that ignores inflation looks smaller than it really is. We default to 5%, the long-run real return of world equities; try 6% or 7% to see how sensitive the timeline is.

The age you see is an estimate, not a guarantee. Real returns vary year to year, and a poor sequence of returns early on can change the outcome. Treat it as a starting point, then run a more detailed version with the calculators above.