FIRE Number Calculator
Find your financial independence number — the portfolio that can fund your spending using the 4% rule — and estimate how long it takes to get there.
Calculator
Lean FIRE (70% of spending): $700,000.00 · Fat FIRE (150% of spending): $1,500,000.00.
On track to financial independence
15.9 yrsYou're 10% of the way there. Investing $2,000.00 a month at a 7% return reaches your $1,000,000.00 FI number in about 15.9 years.
Projected portfolio vs FI number
Show data table
| Year | Portfolio |
|---|---|
| 0 | $100,000.00 |
| 1 | $132,014.00 |
| 2 | $166,343.00 |
| 3 | $203,153.00 |
| 4 | $242,624.00 |
| 5 | $284,948.00 |
| 6 | $330,332.00 |
| 7 | $378,997.00 |
| 8 | $431,180.00 |
| 9 | $487,136.00 |
| 10 | $547,136.00 |
| 11 | $611,473.00 |
| 12 | $680,462.00 |
| 13 | $754,438.00 |
| 14 | $833,761.00 |
| 15 | $918,819.00 |
| 16 | $1,010,026.00 |
An estimate using a fixed return and a fixed withdrawal rate (the "4% rule"), not financial advice. Real returns vary year to year, and fees, taxes, and inflation reduce growth.
About this calculator
Your FIRE number — short for Financial Independence, Retire Early — is the size of an investment portfolio that could fund your spending indefinitely without a paycheck. It is built from one idea: a "safe withdrawal rate", the share of your portfolio you draw each year. The most-cited figure is the 4% rule, which works out to 25 times your annual spending. This calculator turns your own spending into that target, shows how far along you are, and estimates how many years of investing it takes to get there.
How to read your results
The headline is your FI number: annual spending divided by your withdrawal rate (so 4% means 25×, while a more cautious 3% means about 33×). "% to FI" is how much of that target your current portfolio already covers, and "years to FI" projects how long your monthly investing takes to close the rest, compounding at the return you assume. The Lean and Fat FIRE figures reframe the same target for a leaner (70% of spending) or more comfortable (150%) lifestyle. Treat the year count as a rough trajectory, not a promise — markets do not return a smooth fixed percentage.
Worked example
Annual spending of $50,000, the classic 4% withdrawal rate, $200,000 already invested, $3,000 invested each month, and a 7% expected annual return.
The FI number is $1,250,000 ($50,000 ÷ 0.04, i.e. 25× spending). With $200,000 invested you are 16% of the way there. Investing $3,000 a month and compounding at 7% reaches the target in about 13.0 years. For reference, Lean FIRE (70% of spending) would be $875,000 and Fat FIRE (150%) would be $1,875,000.
Frequently asked questions
What is the 4% rule and where does the 25× multiple come from?
The 4% rule is a rule of thumb suggesting you can withdraw about 4% of your portfolio in the first year of retirement, then adjust that amount for inflation, with a good chance the money lasts roughly 30 years. Because 1 ÷ 0.04 = 25, a 4% rate is the same as needing 25 times your annual spending. It comes from historical-market studies (such as the "Trinity study") and is a planning shortcut, not a guarantee — your own safe rate depends on your time horizon, asset mix, fees, and taxes.
How is this different from a retirement savings calculator?
They overlap, but the framing differs. A retirement calculator usually starts from a target retirement age and asks whether your savings will last. A FIRE number starts from your spending and the withdrawal-rate rule to define the portfolio that makes work optional at any age — the goal is financial independence, not a fixed retirement date. Use this to set the target, then a retirement-savings or compound-interest calculator to stress-test the path.
Why do the years-to-FI feel optimistic?
The projection compounds at a single fixed return every month, with no down years, fees, or taxes. Real markets are volatile, inflation erodes spending power, and a bad run of returns early in retirement (sequence-of-returns risk) can shorten how long a portfolio lasts. Use a conservative return, lean toward a lower withdrawal rate, and treat the result as a trajectory to revisit, not a countdown.
Should I use a 3%, 4%, or 5% withdrawal rate?
A lower rate (3%) builds in more safety margin for long retirements or uncertain markets but demands a larger portfolio (about 33×). A higher rate (5%) needs a smaller portfolio (20×) but carries more risk of running short, especially over a long horizon. 4% is the common middle ground. The right choice depends on your retirement length, flexibility to cut spending, and risk tolerance — this is a personal decision, not financial advice.
How it's calculated
FI number = annual spending ÷ (withdrawal rate ÷ 100). The 4% rule comes from studies of historical portfolios suggesting a roughly 4% first-year withdrawal (adjusted for inflation thereafter) tends to last about 30 years — hence the familiar 25× multiple. Lower rates give a larger, safer multiple; higher rates a smaller, riskier one. Progress is current portfolio ÷ FI number, capped at 100%. Years to FI is found by stepping month by month: each month the balance earns one-twelfth of the annual return and then your monthly contribution is added, until the balance reaches the FI number (capped at 100 years; if you are already at the target it is zero). Lean FIRE = 70% of spending and Fat FIRE = 150% of spending, run through the same withdrawal-rate formula. Everything assumes a single fixed return and a fixed withdrawal rate; it is a planning aid, not financial advice.
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