FIRE Number Calculator
Calculate the Financial Independence number you need to retire early, with Lean FIRE, Fat FIRE and Coast FIRE variants and years-to-FI projection.
Written by Rahman · Last reviewed
Quick answer
At the commonly cited 4% withdrawal rate your FIRE number is 25× annual spending; at a more cautious 3.5% it is 28.6× and at 3% it is 33×. So the target is driven entirely by what you spend rather than what you earn — cutting annual expenses by $1,000 lowers the number you need by $25,000 at 4%, and by $33,000 at 3%.
Year-by-year projection
Scroll to see the path from today to FIRE. Milestone column flags when each tier (Coast / Lean / FIRE / Fat FIRE) is hit.
| Yr | Age | Contributed | Balance | % to FIRE | Milestone |
|---|---|---|---|---|---|
| 1 | 31 | 124,000 | 131,840 | 10.5% | 🏖️ Coast FIRE |
| 2 | 32 | 148,000 | 165,909 | 13.3% | |
| 3 | 33 | 172,000 | 202,362 | 16.2% | |
| 4 | 34 | 196,000 | 241,368 | 19.3% | |
| 5 | 35 | 220,000 | 283,104 | 22.6% | |
| 6 | 36 | 244,000 | 327,761 | 26.2% | |
| 7 | 37 | 268,000 | 375,544 | 30.0% | |
| 8 | 38 | 292,000 | 426,672 | 34.1% | |
| 9 | 39 | 316,000 | 481,379 | 38.5% | |
| 10 | 40 | 340,000 | 539,916 | 43.2% | |
| 11 | 41 | 364,000 | 602,550 | 48.2% | |
| 12 | 42 | 388,000 | 669,568 | 53.6% | |
| 13 | 43 | 412,000 | 741,278 | 59.3% | |
| 14 | 44 | 436,000 | 818,008 | 65.4% | |
| 15 | 45 | 460,000 | 900,108 | 72.0% | |
| 16 | 46 | 484,000 | 987,956 | 79.0% | 🌱 Lean FIRE |
| 17 | 47 | 508,000 | 1,081,953 | 86.6% | |
| 18 | 48 | 532,000 | 1,182,529 | 94.6% | |
| 19 | 49 | 556,000 | 1,290,146 | 100.0% | 🎯 FIRE! |
| 20 | 50 | 580,000 | 1,405,296 | 100.0% | |
| 21 | 51 | 604,000 | 1,528,507 | 100.0% | |
| 22 | 52 | 628,000 | 1,660,343 | 100.0% | |
| 23 | 53 | 652,000 | 1,801,407 | 100.0% | |
| 24 | 54 | 676,000 | 1,952,345 | 100.0% | 💎 Fat FIRE |
The FIRE number is your annual expenses divided by your safe withdrawal rate (the Trinity Study popularised 4% as a rate that historically lasted 30+ years). Lean and Fat FIRE adjust for a leaner or more luxurious lifestyle. Coast FIRE is the amount needed today that, without any further contributions, grows to your full FIRE number by age 65 — 35 years away at your current age, at your assumed return.
Results are estimates for general guidance and are not financial, tax or legal advice. Except where a calculator names a currency, figures carry no currency of their own — put in pounds and you get pounds back, put in rupees and you get rupees. Figures depend on the assumptions you enter and on rates that change over time — check current rates and speak to a qualified adviser before acting on them.
About the FIRE Number Calculator
FIRE (Financial Independence, Retire Early) is the goal of accumulating enough invested assets that your investment returns can cover your living expenses indefinitely. The "FIRE number" is how much that takes — typically your annual expenses divided by a safe withdrawal rate of 3–4%.
The 4% rule comes from the Trinity Study, which showed that a portfolio of 50–75% stocks and the rest in bonds had a high probability of lasting 30+ years if you withdrew 4% in the first year and adjusted for inflation thereafter. More conservative FIRE planners use 3–3.5%; more aggressive ones go up to 5%.
FIRE number = annual_expenses ÷ safe_withdrawal_rate
Variants: Lean FIRE = 75% of expenses, Fat FIRE = 150% of expenses. Coast FIRE = today's investment that grows to the FIRE number by traditional retirement age without further contributions.
If your annual expenses are $50,000 and you use a 4% safe withdrawal rate, your FIRE number is $1,250,000. Starting from $100,000 in current savings and adding $2,000/month at a 7% real return, you'd reach FIRE in about 18.6 years. Lean FIRE ($37,500/year expenses) would cut the target to $937,500; Fat FIRE ($75,000/year) raises it to $1,875,000. Coast FIRE — the amount you'd need today that grows to $1.25M by age 65 (35 years away at a starting age of 30) at 7% — is just $117,000.
What the 4% rule actually claimed
The multiple behind every FIRE number comes from research into how long a portfolio survived historical drawdowns. The finding was that a 4% initial withdrawal, increased annually with inflation, survived a 30-year retirement across the historical US record for a stock-and-bond portfolio. Twenty-five times spending is simply the reciprocal of that.
Two assumptions inside it matter for early retirement specifically. The horizon studied was 30 years, and someone retiring at 40 may need 50 or more. And the data is a single country's history, during the century in which it became the dominant economy — a favourable sample, not a neutral one.
- Longer horizons push the safe rate down. Many early-retirement analyses use 3% to 3.5%, which raises the target from 25× to between 28.6× and 33.3× spending.
- Funding $40,000 a year needs $1,000,000 at 4%, $1,142,857 at 3.5%, or $1,333,333 at 3%. The spending assumption did not change — only the confidence level did.
- Fees come out of the same withdrawal. A 1% platform and fund charge against a 4% withdrawal consumes a quarter of the income.
The gaps a single number cannot cover
A FIRE number prices ongoing spending. It does not price the structural problems that come with leaving work decades early, and those are usually what determines whether the plan holds.
Healthcare is the largest in the US, where employer cover ends and Medicare does not begin until 65 — a gap that can run for decades and whose cost is neither stable nor predictable. Accessing retirement accounts before 59½ also requires specific strategies rather than simple withdrawals, and the sequence of early returns matters far more when the drawdown period is long.
- Coast FIRE means the invested balance will reach the target on its own without further contributions; it does not mean work can stop, only that saving can.
- Lean and Fat FIRE describe different spending assumptions rather than different rules, so they change the target and nothing else.
- Flexibility is worth more than precision. A plan that can cut spending in poor years survives conditions that a fixed withdrawal does not.
FIRE number at different SWR and expenses
| Annual expenses | 3% SWR | 4% SWR | 5% SWR |
|---|---|---|---|
| $30,000 | $1,000,000 | $750,000 | $600,000 |
| $50,000 | $1,666,667 | $1,250,000 | $1,000,000 |
| $75,000 | $2,500,000 | $1,875,000 | $1,500,000 |
| $100,000 | $3,333,333 | $2,500,000 | $2,000,000 |
Choosing 3% vs 4% safe withdrawal rate adds ~33% to your target FIRE number — meaningful enough to be worth understanding the sequence-of-returns risk that drives the choice.
Frequently Asked Questions
Is the 4% rule still safe?
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It has held up well historically, but assumes a 30-year retirement and a US stock/bond mix. For a 50-year FIRE retirement, many planners prefer 3-3.5% to provide more buffer against the sequence-of-returns risk early in retirement.
What is Coast FIRE?
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Coast FIRE is the amount you need invested today that, with no further contributions, will grow to your full FIRE number by traditional retirement age (~65). After hitting Coast FIRE, you only need to earn enough to cover living expenses — investing more becomes optional.
What about taxes in retirement?
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The simple FIRE formula uses gross withdrawals. In practice, withdrawals from traditional retirement accounts are taxable, Roth withdrawals are tax-free, and brokerage withdrawals are taxed at capital-gains rates. A well-diversified mix can keep effective tax rates low.
What about healthcare before Medicare?
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A key challenge for early retirees in the US — Medicare starts at 65. Plan for $15,000–$25,000/year in ACA marketplace premiums for a couple, varying by state and income. Many FIRE plans add this explicitly to annual expenses.
Does inflation affect the FIRE number?
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Use today's dollars for both your expenses and your assumed return. The 4% rule already incorporates inflation-adjusted withdrawals. If you use a nominal return, your FIRE number should also be in future inflated dollars — most planners avoid this complexity by working in real (inflation-adjusted) terms.
Sources
- Morningstar — The Good News on Safe Withdrawal Rates — Morningstar re-derives a starting safe withdrawal rate each year, and its own figure has moved from 3.3% to 3.8% to 4.0% (the latest, at a 90% probability of funds remaining over a 30-year horizon) as bond and cash yields changed. Cited as evidence for the framing on this page: the safe rate is a periodically re-estimated output of market conditions and horizon, not a fixed law, which is exactly why the 3% to 3.5% figures used in early-retirement planning are not a contradiction of it.