Quick answer
Your FIRE number is the portfolio size that lets investment returns alone cover your annual expenses. The starting formula is annual expenses × 25 (the 25× rule). For a 40–50 year early retirement, multiplying by 28–30 instead is the 2026 best practice — a more conservative withdrawal rate of 3.3–3.5%.
What is a FIRE number?
The portfolio size that lets investment returns alone fund your annual expenses indefinitely.
Your FIRE numberis the value your investment portfolio needs to reach so that you can stop earning income from work and live off the portfolio indefinitely. It is the practical translation of “financial independence” into a single dollar (or euro) figure.
The number is not a ceiling on lifestyle. It is the threshold at which paid work becomes optional. You can still earn — many people who reach FIRE keep working in some form — but the math no longer requires it.
The 25× rule and where it comes from
Why the 4% rule and the 25× rule are the same equation.
The 25× rule comes from the 4% safe withdrawal rateestablished by the 1998 Trinity Study and Bill Bengen's earlier 1994 paper. The math is simply the inverse:
If you spend $50,000 per year, the headline FIRE number is $1,250,000. The Trinity Study showed that a 50/50 to 75/25 stocks/bonds portfolio supported a 4% inflation-adjusted withdrawal across nearly all rolling 30-year periods of US history.
Why 25× is too aggressive for early retirees
A 50-year retirement breaks the Trinity Study's 30-year assumption.
The Trinity Study's 30-year horizon assumed traditional retirement age. Retire at 40 and live to 90 — and many will — and you have a 50-year retirement to fund. That is not what 4% was designed for.
The Big ERN safe-withdrawal-rate research, the most-cited modern source on this, finds that for 50-year retirements 3.25–3.50% would have survived even the worst historical sequences, including the 1929 and 1966 starts. Translated into multiples:
| Withdrawal rate | Multiple | Typical horizon |
|---|---|---|
| 4.0% | 25× | 30 years |
| 3.5% | 28.6× | 40 years |
| 3.3% | 30.3× | 50 years |
| 3.0% | 33.3× | 50+ years, conservative |
Read the deep dive in Safe Withdrawal Rate.
2026 benchmark FIRE numbers
Worked examples at common spending levels using a conservative 3.5% withdrawal rate.
Using a conservative 3.5% withdrawal rate against the classic 4% baseline:
| Annual spending | 25× (4% rule) | 28.6× (3.5% rule) | FIRE type |
|---|---|---|---|
| $25,000 | $625,000 | $715,000 | Lean FIRE |
| $40,000 | $1,000,000 | $1,143,000 | Lean / Regular |
| $60,000 | $1,500,000 | $1,715,000 | Regular FIRE |
| $100,000 | $2,500,000 | $2,860,000 | Fat FIRE |
| $150,000 | $3,750,000 | $4,290,000 | Fat FIRE |
How to calculate your own FIRE number
Four steps from your real annual spending to a personal target.
- Estimate your real annual spending in retirement — not what you spend today on average, but what you would actually spend with no commute, more travel, and (in the US) post-employer healthcare costs.
- Pick a withdrawal rate. Use 4% only if you plan a ≤ 30-year retirement. Use 3.5% for 40 years, 3.3% for 50.
- Divide spending by the withdrawal rate. $50,000 ÷ 0.035 = $1,428,571.
- Adjust for non-portfolio income. Pension, Social Security, rental income — subtract these from your spending before applying the multiplier.
The free FIRE Calculator runs all four steps in seconds, plus inflation-adjusted projections so the result is in today's purchasing power.
FIRE number ≠ retirement plan
Reaching the number is necessary but not sufficient — sequence risk and spending creep can still derail you.
Reaching the number is necessary but not sufficient. Two pitfalls trip up first-timers.
Sequence of returns risk. A 30% drawdown in your first two retirement years can permanently impair the portfolio even if average returns are fine. See Sequence of Returns Risk.
Spending creep. The number is denominated in current spending. Three years of casually upgrading your lifestyle can add 15% to it. The fix is to revisit spending annually and tie any large lifestyle changes to a portfolio milestone, not a feeling.