FIRE Number Calculator
Enter what you actually spend in a year, pick a withdrawal rate, and the calculator gives your FIRE number - the invested sum whose returns fund that spending forever - plus the remaining gap and how many years your current pot needs to coast there untouched.
Most FIRE calculators fix the 4% rule and flatter the result. This one exposes the rate choice - 4% is a 30-year US study, early retirees run 3.25-3.5% for 50-year horizons - and prices the trade honestly instead of selling a course.
How to use
- Enter true annual spending from last year's records, not an aspirational budget.
- Choose the rate for your retirement length: 4% for classic 30-year, 3.25-3.5% if retiring decades early.
- Read the gap, the coast years (what happens if you never save again), and the passive income at target.
Frequently asked questions
What is the 25x rule?
FIRE number equals 25 times annual spending - the inverse of the 4% withdrawal rate from the Trinity study. It is a starting point: long retirements warrant 28-30x (3.5-3.25%), and the number scales with spending, not salary.
Why do early retirees use 3.5% instead of 4%?
The 4% rule was tested over 30-year retirements at age 65. A 35-year-old needs the money to last 50+ years, through more market cycles and unknown future costs - the extra margin turns a coin-flip into a robust plan.
Is the FIRE number a guarantee?
No - it is a floor built on historical averages. Sequence-of-returns risk means a crash in the first retired years bites hardest; flexible rules (spend 10% less after down years) buy more safety than a bigger number ever did.
What counts as annual expenses?
Everything you actually spent last year including the irregular - repairs, insurance, holidays - averaged in. Using your aspirational budget produces a number that funds the person you wish you were, not the one who wakes up on Tuesday.