Home / FIRE basics / What is FIRE? Financial independence in numbers
FIRE basicsWhat is FIRE? Financial independence in numbers
FIRE means saving and investing until your portfolio pays for your life, so work becomes optional. The letters stand for financial independence, retire early. Under the 4% rule that takes about 25 times your annual spending: $1,000,000 for $40,000 a year.
What FIRE means
Financial independence (FI) is the point where your investments can pay for your spending, so you no longer need a paycheck. Retiring early (RE) is optional. Many people who reach FI keep working, change careers or work part time, and the difference is that they choose to.
The usual target comes from the 4% rule. William Bengen tested withdrawal rates against US market history in 1994, and a first-year withdrawal of 4% of the portfolio, raised with inflation every year after, became the best-known result of his work and of the 1998 Trinity study. Dividing your spending by 4% is the same as multiplying it by 25.
The five versions in one table
The same household in every row: 35 years old, $100,000 invested, saving $25,000 a year, 5% a year after inflation and a 4% withdrawal rate.
| Version | Portfolio pays | Portfolio needed | Reached at age |
|---|---|---|---|
| Lean FIRE | $25,000 a year | $625,000 | 47.9 |
| Regular FIRE | $40,000 a year | $1,000,000 | 53.8 |
| Fat FIRE | $100,000 a year | $2,500,000 | 68.0 |
| Coast FIRE | $40,000 a year from 65 | $313,841 | 41.2 |
| Barista FIRE | $20,000 a year | $500,000 | 45.5 |
Lean, regular and fat FIRE differ only in the budget. Coast FIRE stops the saving early and keeps the work; barista FIRE replaces part of the spending with part-time income. The trade-offs of each are in lean vs fat vs coast vs barista FIRE.
How much you need
| Spending a year | At 4% | At 3.5% |
|---|---|---|
| $30,000 | $750,000 | $857,143 |
| $40,000 | $1,000,000 | $1,142,857 |
| $60,000 | $1,500,000 | $1,714,286 |
| $100,000 | $2,500,000 | $2,857,143 |
A 3.5% rate is more cautious and often tested for retirements longer than 30 years. More spending levels and the formula are in how to calculate your FIRE number.
Is FIRE realistic?
It depends mostly on your savings rate, the share of your income you save. In Mr. Money Mustache's 2012 example, saving 10% of a $50,000 income takes about 51 years; our formula gives 51.4 years. Saving half of the same income cuts it to 16.6 years, because you save more and also need less: $25,000 a year instead of $45,000.
Both figures start from zero and assume 5% a year after inflation, a 4% withdrawal rate and no taxes or fees. Lower returns, higher costs or a bad run of years make the path longer.
These figures are illustrations worked out from stated assumptions, not forecasts. Real returns vary from year to year, and taxes, fees and the order of good and bad years change the outcome. See the disclaimer.
A short history
| Year | Milestone |
|---|---|
| 1992 | Your Money or Your Life, by Vicki Robin and Joe Dominguez, sets out the idea of spending less and living on investment income. |
| 1994 | William Bengen publishes the research behind the 4% withdrawal rate. |
| 1998 | The Trinity study tests withdrawal rates against US stock and bond returns. |
| 2010 | Jacob Lund Fisker's Early Retirement Extreme links the savings rate to the years of work needed. |
| 2011 | Peter Adeney starts the Mr. Money Mustache blog, which helps popularize FIRE online. |
Common mistakes
- Treating 25 times spending as a guarantee. The 4% rule describes what worked historically over about 30 years. For retirements of 50 years or more, Karsten Jeske's Early Retirement Now series argues for 3.25% to 3.5%; at 3.5%, $40,000 a year needs $1,142,857.
- Mixing returns before and after inflation. A 7% return with 3% inflation is 3.88% after inflation, a little less than the 4% you get by subtracting. Using 7% as if it were real made the example in the FIRE calculator look 4.7 years shorter than it is.
- Leaving out health insurance and taxes. Medicare generally starts at 65, so an early retiree pays for health coverage until then. Both belong in your annual spending.
Questions people ask
What is the 4% rule in the FIRE movement?
It is the rule of thumb behind the usual FIRE number: if you can live on 4% of your portfolio in the first year and raise that amount with inflation, the portfolio has to be 25 times your annual spending. It comes from studies of retirements of about 30 years, so many early retirees also test 3.5% or less; see the 4% rule explained.
How much money do you need for financial independence to retire early?
About 25 times what you spend in a year at a 4% withdrawal rate, or about 28.6 times at 3.5%. Spending $40,000 a year, that is $1,000,000 or $1,142,857; spending $60,000, $1,500,000 or $1,714,286.
What is the $1000 a month rule for retirees?
It is a shortcut for the savings needed to produce a monthly income. $1,000 a month is $12,000 a year, which at a 5% withdrawal rate needs $240,000 saved, so the rule says $240,000 for each $1,000 a month. At the 4% rate used for FIRE the same $1,000 a month needs $300,000.
Can I retire at 45 with $3 million dollars?
That depends on what you spend. A retirement that starts at 45 may need to last 50 years, and Morningstar's starting rate for 50 years is 2.9%: on $3,000,000 that is a first-year withdrawal of $87,000. At 4% it would be $120,000. Health insurance until Medicare at 65 belongs in that spending.
Try it with your numbers
The FIRE calculator gives your FIRE number and the age you reach it for lean, regular and fat FIRE; the coast FIRE calculator tells you when you could stop saving.
Sources
- Vicki Robin and Joe Dominguez, Your Money or Your Life, 1992.
- William P. Bengen, "Determining Withdrawal Rates Using Historical Data", Journal of Financial Planning, October 1994.
- Philip L. Cooley, Carl M. Hubbard and Daniel T. Walz, "Retirement Savings: Choosing a Withdrawal Rate That Is Sustainable", AAII Journal, February 1998 (the Trinity study).
- Jacob Lund Fisker, Early Retirement Extreme, 2010.
- Mr. Money Mustache, "The Shockingly Simple Math Behind Early Retirement", January 13, 2012.
- Karsten Jeske, The Safe Withdrawal Rate Series, Early Retirement Now (blog series, 2016 onward).
- Amy C. Arnott, "How Much Can You Safely Withdraw If You Retire Early?", Morningstar, September 15, 2026 (data as of September 30, 2025).
Last reviewed by Asier Fernández, editor, on . Educational information only, not financial advice. How we calculate