Your FIRE number is the portfolio that lets you live off withdrawals forever. The formula is simple: divide your annual spending by your safe withdrawal rate. At the classic 4% rate that is the same as multiplying spending by 25 — so $50,000 of spending needs a $1,250,000 portfolio. That same base number is what later gets reshaped into Coast FIRE and Barista FIRE strategies.
FIRE number by spending level
Here is the target at a 4% withdrawal rate (25× spending):
| Annual spending | FIRE number (4% / 25×) |
|---|---|
| $40,000 | $1,000,000 |
| $50,000 | $1,250,000 |
| $60,000 | $1,500,000 |
| $80,000 | $2,000,000 |
| $100,000 | $2,500,000 |
The formula
For $50,000 of spending at a 4% rate: $50,000 ÷ 0.04 = $1,250,000. Because dividing by 4% is the same as multiplying by 25, you'll often see it written as the “25× rule.” The multiplier moves with the withdrawal rate you choose.
Why is FIRE based on 25× spending?
The 25× rule comes directly from the 4% rule. If 4% of a portfolio can fund one year of spending, you need the inverse of 4% to find the full portfolio:
It is a useful planning shortcut, not a promise that every portfolio will last forever. The original 4% research focused on roughly 30-year retirements; early retirees often test lower withdrawal rates and flexible spending too. See the 4% rule guide for the risks behind the shortcut.
How big is your FIRE number?
There is no universal “normal” FIRE number because the target follows your lifestyle. These benchmarks show the scale at a 4% withdrawal rate:
If your target sits near the lean range, read how much is enough for Lean FIRE before treating the 25× result as your final number. A low budget often has less optional spending to cut after a market decline. For the broader map of where full, Coast, and Barista paths fit, see Types of FIRE. If you are targeting a more comfortable middle ground, the Chubby FIRE guide shows what a larger FIRE number buys.
| Lifestyle benchmark | Annual spending | FIRE number |
|---|---|---|
| Lean | $40,000 | $1,000,000 |
| Moderate | $60,000 | $1,500,000 |
| Comfortable | $100,000 | $2,500,000 |
| High-spend | $150,000 | $3,750,000 |
FIRE number vs. annual spending at a 4% withdrawal rate
How the withdrawal rate changes your number
The withdrawal rate is the single biggest lever on the formula. For $50,000 of spending:
| Withdrawal rate | Multiplier | FIRE number |
|---|---|---|
| 3.25% | 30.8× | $1,538,000 |
| 3.5% | 28.6× | $1,429,000 |
| 4% | 25× | $1,250,000 |
| 4.5% | 22.2× | $1,111,000 |
Dropping from 4% to 3.5% raises a $1,250,000 target to about $1,429,000 — a $179,000 difference for the exact same spending, just from a safer assumption.
Why spending matters more than returns
Your withdrawal rate matters, but annual spending is usually the most controllable lever. Cutting spending from $50,000 to $45,000 lowers a 4% FIRE target from $1,250,000 to $1,125,000. That is a $125,000 smaller target from a $5,000 lifestyle change.
Chasing higher investment returns can make a projection look better, but future returns are uncertain and outside your control. Spending less has an immediate, predictable effect: every permanent $1,000 annual reduction removes $25,000 from a 4% FIRE number.
What counts as spending in your FIRE number?
Start with what your retirement lifestyle will actually cost, not your salary or current savings target. Include recurring costs and convert irregular bills into annual averages.
- Include: housing, food, transportation, utilities, healthcare, taxes, insurance, travel, hobbies, home repairs, and other irregular expenses.
- Exclude: retirement contributions and other savings that stop once you retire.
- Handle debt by timeline: include mortgage payments if they continue into retirement; exclude principal and interest after the loan is paid off.
Early retirees should explicitly account for healthcare before Medicare eligibility. Costs depend on household income, location, plan choice, and subsidies, so use the health insurance before Medicare guide instead of relying on one generic estimate.
Use more than one spending scenario
Retirement spending rarely stays flat. Model a baseline, a comfortable plan, and a high-cost scenario. A paid-off mortgage may lower later spending, while healthcare or travel may make earlier years more expensive.
Common mistakes
1. Confusing the FIRE number with the date. Two people with the same $1,250,000 target can reach it a decade apart depending on savings rate and starting balance.
2. Using gross-of-fee returns. A 1% fund fee quietly raises the portfolio you actually need; model your return net of fees.
3. Counting Social Security twice. Either subtract expected benefits from the spending your portfolio must cover or model them as future income. Do not do both.
FIRE number FAQ
Is 4% still safe?
The 4% rule is a historical planning baseline, not a guarantee. Your retirement length, asset allocation, fees, taxes, and willingness to reduce spending after poor market years all affect the result. Many early retirees also test 3.25% or 3.5%.
What if I retire before 65?
Include the cost of health insurance before Medicare and test a longer retirement horizon. Retiring earlier generally makes conservative withdrawal rates and flexible spending more important.
Does Social Security reduce my FIRE number?
Yes, expected Social Security can reduce the amount your portfolio must fund after benefits begin. Because benefits arrive later, a simple 25× calculation can miss the bridge years; model the timing separately.
Should I include taxes?
Yes. Taxes are spending. Estimate the tax bill created by your account mix and withdrawal plan, then include it in annual expenses.
Is the 25× rule enough?
It is enough for a first estimate. A retirement decision should also test lower withdrawal rates, market downturns, changing expenses, healthcare, taxes, and future income. Review the FIRE methodology and assumptions before treating the target as final.
What to read next
All projections assume a fixed annual return and inflation rate and no withdrawals. Past market returns do not guarantee future results. This article is educational and does not constitute financial advice.