Your FIRE number is the portfolio size that lets work become optional. Enter the annual spending you want in retirement and your planned withdrawal rate, and this calculator applies the 25× rule to show the nest egg you need — plus lean, fat, and conservative 3%-rule variations. Ready to map the path to that number? Open the full retirement calculator.
Your FIRE number is yearly spending ÷ your withdrawal rate. At the classic 4% rule, that's spending × 25 — so $40,000 a year needs a $1,000,000 portfolio.
The 4% rule (and its 25× shortcut) comes from research suggesting a portfolio can sustain ~4% of its starting value, adjusted for inflation, for about 30 years.
Lean FIRE assumes a leaner budget (here, 70% of your spending) and fat FIRE a more generous one (150%) — the same math on a different lifestyle.
The conservative 3% rule (spending × 33.3) builds a bigger cushion for early retirees whose money must last far longer than 30 years.
It's the shortcut behind the 4% rule: multiply the annual spending you want in retirement by 25 to estimate the portfolio you need. It's the inverse of withdrawing 4% per year (1 ÷ 0.04 = 25).
Should I use 4% or 3%?
4% is the classic figure for a roughly 30-year retirement. If you're retiring early and your money must last 40–50+ years, a more conservative 3% (a larger FIRE number) gives extra safety margin.
Does my FIRE number include Social Security or CPP?
No — it's based purely on your own portfolio funding your spending. Government benefits like US Social Security or Canada's CPP/OAS reduce how much you personally need, so treat this as a conservative, savings-only target.