Enter what you make, what you spend, and what you've saved — see your FI number, your savings rate, and roughly how many years until work is optional.
The FIRE math
FI number = annual spending ÷ withdrawal rate (4% → spending × 25)
years = how long current savings + yearly saving compound to reach it
Everything is in today's dollars: using an after-inflation return means the answer doesn't need inflation adjustments layered on top. The two levers are visible in the formula — spend less and the target shrinks while savings grow; earn more and only the savings side moves. That asymmetry is why the FIRE community obsesses over spending.
A worked example
Take home $70,000, spend $50,000, with $60,000 invested: you save $20,000 a year (a 29% savings rate) toward an FI number of $1.25 million. At 5% real returns, that compounds to the target in roughly 24 years. Cut spending to $42,000 and the same math says 18 — the $8,000 did double duty.
What this calculator won't pretend to know
Markets don't return 5% in a straight line, healthcare before 65 is a real planning problem, and most people's income and spending change more over 20 years than any model captures. The FIRE community's own answer to this is the right one: recompute yearly, stay flexible, and treat the years number as a direction of travel rather than a promise.
Frequently asked questions
What is FIRE?
Financial Independence, Retire Early — a movement built around one idea: once your invested savings can cover your spending forever, work becomes optional. The name and the math conventions come from the online FIRE community, which has refined them over two decades.
What is the 4% rule?
A guideline from the Trinity study: a portfolio can typically sustain withdrawals of about 4% of its starting value per year, adjusted for inflation, for 30+ years. Flip it around and you get the FI number: annual spending × 25.
What savings rate do I need to retire early?
Savings rate is the whole game. Saving 10% of take-home means roughly 50 working years; 25% about 32 years; 50% about 17; 65% about 10. Cutting spending counts double — it raises the savings rate and lowers the target at the same time.
Is the 4% rule safe?
It's a planning guideline, not a guarantee — early retirees with 50-year horizons often plan around 3.5%, and flexibility (spending less in bad market years, some part-time income) matters more than the exact decimal. Treat the output here as a compass, not a contract.