Your FIRE number is your annual spending divided by your withdrawal rate — 25× spending at the classic 4%. Change any figure and the number, the date and the odds all update as you type.
Your FIRE number
$1,250,000
$50,000/yr ÷ 4% = 25× your annual spending
| Withdrawal rate | You would need | Multiple of spending |
|---|---|---|
| 3% | $1,666,667 | 33× |
| 3.5% | $1,428,571 | 29× |
| 4% · yours | $1,250,000 | 25× |
| 5% | $1,000,000 | 20× |
You reach it at
Age 54
≈ 2045 · in ~19 yrs
Money lasts to 95
80%
of 1,000 simulations
1,000 simulated futures · 7% real return, 15% volatility · drawn down to age 95
FIRE number = annual spending ÷ safe withdrawal rate. That is the whole thing. Spending $50,000 a year at a 4% withdrawal rate needs $1,250,000, because 4% of $1.25M is exactly $50,000. Flip the rate to 3% and the same life costs $1,666,667 — a third more, for a single assumption most calculators bury.
Income decides how fast you get there; spending decides where “there” is. Two people earning the same can have FIRE numbers a million dollars apart purely because one plans to live on $40,000 and the other on $80,000. It is worth spending real effort on that one number — every other input matters less.
The 4% rule comes from the Trinity study, which tested roughly 30-year retirements. Retiring at 40 can mean funding 50 years or more, and the same rate is doing a harder job over that span — which is why many early retirees plan at 3% to 3.5% instead. The simulation above does not assume the rule holds; it draws 1,000 market paths and reports how often the money actually lasted. The full method is public.
Beyond a one-time estimate
Save the plan and Fire Horizon re-checks your number against your real accounts — every day, free.
Runs on your real money
Link a brokerage with Plaid or drop in a CSV, and this exact chart tracks your actual balances — updating as markets move and you invest. No more re-typing estimates.
Tells you if you’re on track
Your Readiness score re-runs this Monte Carlo on your real net worth and answers what matters: on track for your age, will it last, is your emergency fund covered.
Your whole net worth, in one place
Investments, cash, property and debts together — with a savings rate pulled from your real deposits and your dividend income counted. All free.
Same math here and inside — every formula is hand-checkable on the methodology page.
More free calculators
Weighing up the options? See how the best FIRE calculators compare.
Watch the gap close.
Link a brokerage or import a CSV and Fire Horizon tracks how far you actually are from your number — priced daily, on your real holdings.
Create your free accountNot financial advice — projections are estimates based on your assumptions