How the FIRE number is calculated
Your FIRE number is the size of investment portfolio that can fund your lifestyle indefinitely. It comes from the safe withdrawal rate:
FIRE number = Annual spending ÷ Safe withdrawal rate
At a 4% withdrawal rate, that's simply your annual spending × 25. So if you spend $40,000 a year, you'd aim for a $1,000,000 portfolio. The idea, based on the well-known Trinity Study, is that a diversified portfolio can sustain roughly 4% annual withdrawals (adjusted for inflation) over a long retirement.
The three levers of early retirement
- Spend less: lower spending shrinks your FIRE number and raises your savings rate — a double win.
- Save more: your savings rate is the biggest driver of how soon you reach FI.
- Invest wisely: consistent, low-cost investing lets compounding accelerate your timeline.
Tools to get there faster
Low-cost investing
Most of the FIRE community builds wealth with broad, low-fee index funds.
Compare brokers →Net-worth tracking
Seeing your savings rate and net worth in one place keeps you on plan.
See tools →Frequently asked questions
Is the 4% rule safe?
It's a strong rule of thumb for a ~30-year retirement, but early retirees with 40–50 year horizons often use a more conservative 3.25–3.5%. Lower the withdrawal rate for a bigger safety margin.
Does this include inflation?
Use a "real" (after-inflation) return — around 7% historically becomes ~5% real. The withdrawal rate already assumes inflation-adjusted spending.
What about Social Security or a pension?
This calculator focuses on portfolio-funded independence. Future guaranteed income would reduce the portfolio you need.