FIRE Calculator
Find your financial independence (FI) number and how long it takes to reach it. Enter your take-home income, spending, investments, expected real return and withdrawal rate; switch to Coast FIRE or Barista FIRE to test the in-between paths.
How to Use
- Choose FIRE for full financial independence, Coast FIRE to see when you could stop saving, or Barista FIRE if part-time work will pay some of your bills.
- Enter your age, your yearly take-home income and what you spend in a year. The difference is what you invest.
- Enter what you have invested now, the real return you expect (after inflation) and the withdrawal rate you plan to live on, such as 4%.
- For Coast FIRE add the age you would retire anyway; for Barista FIRE add the part-time income you expect.
- Read your FI number, the time to reach it and the age you get there. Open the savings-rate table under the chart to see how much the rate matters.
Worked Example
Saving half at 30. You take home $100,000, spend $50,000 and have $80,000 invested. At a 4% withdrawal rate your FI number is $50,000 ÷ 0.04 = $1,250,000. You invest the other $50,000 a year, $4,166.67 a month, and a 5% real return is (1.05)1/12 − 1 = 0.4074% a month. Solving for the months until $80,000 plus those deposits reaches $1,250,000 gives 178 months: 14 years 10 months, at 44. Of the $1,250,000, $821,667 is money you put in and the rest is growth.
Coast FIRE instead. At 35 with $250,000 invested and a plan to retire at 60 on $50,000 a year, the money must reach $1,250,000 in 25 years. At 5% a year that needs $1,250,000 ÷ 1.0525 = $369,128 today. You are short, but saving $30,000 a year closes the gap in 4 years 6 months; after that, the investments can coast to 60 on their own.
The common mistake: a market return with today’s prices. Plugging in a 7% return, roughly a stock-market average before inflation, while leaving spending at today’s $50,000 says FI in 13 years 2 months. But a $50,000 lifestyle will cost more by then. With 2.5% inflation, the real return is 1.07 ÷ 1.025 − 1 = 4.39%, and the honest answer is 15 years 6 months. Keep everything in today’s dollars and use a return after inflation.
Show Work
Formulas
Where FIRE Came From
The ideas behind FIRE, short for financial independence, retire early, go back to Your Money or Your Life, the 1992 book by Vicki Robin and Joe Dominguez, which asked readers to count their spending in hours of their life and to aim for investment income that covers it. Jacob Lund Fisker’s Early Retirement Extreme (2010) set out the link between savings rate and years to retirement that the table under the chart shows, and the Mr. Money Mustache blog, started by Peter Adeney in 2011, brought the idea to a wide audience.
The target most FIRE plans use comes from retirement research. William Bengen’s October 1994 article in the Journal of Financial Planning looked back over US returns and inflation from 1926 and found that a first-year withdrawal of 4%, raised with inflation each year, had always lasted at least 33 years. In February 1998, finance professors Philip Cooley, Carl Hubbard and Daniel Walz of Trinity University published their own test in the AAII Journal, now known as the Trinity study. Spending ÷ 0.04, or 25 times a year’s spending, became the shorthand.
Both studies looked at 30-year retirements. Someone stopping work at 40 may need money for 50 years or more, which is why many early retirees plan on 3.5% or less and why the withdrawal rate here is an input, not a fixed 4%. In the US, early retirees also have to cover health insurance until Medicare starts at 65.
About This Tool
This calculator works in today’s dollars: you give it a real return, after inflation, so your spending and your FI number never need inflating. It invests the difference between your take-home income and your spending every month, compounds it at that real return and finds the month the balance reaches your FI number. Coast FIRE finds when your investments could grow to the FI number by your chosen age with no more saving; Barista FIRE lowers the target by the part-time income you expect. Lean and Fat FIRE are the same calculation with a smaller or larger budget, as the presets show.
Returns are steady averages and do not include taxes on withdrawals; real markets rise and fall, so leave a margin and run it again each year. Everything runs in your browser; nothing you enter is sent anywhere. Estimates for planning and education — not financial, tax or legal advice.
Related tools: Retirement Withdrawal Calculator, Retirement Calculator, and Budget Calculator.
Frequently Asked Questions
How do I work out my FI number?
Divide what you spend in a year by the withdrawal rate you plan to use. At 4% that is 25 times your spending: $50,000 a year needs $1,250,000. A more cautious 3.5% needs 28.57 times, $1,428,571, and 3% needs $1,666,667. In the calculator’s first preset, saving $50,000 a year from $80,000 at a 5% real return reaches $1,250,000 in 14 years 10 months; the 3% target takes 18 years 4 months.
Where does the 4% rule come from?
From William Bengen’s article in the October 1994 Journal of Financial Planning. Using US stock, bond and inflation data from 1926, he found that withdrawing 4% of a portfolio in the first year and raising the amount with inflation after that never ran out in under 33 years, while 4.25% could run out in 28. Three Trinity University finance professors, Cooley, Hubbard and Walz, tested withdrawal rates again in the February 1998 AAII Journal. Both looked at retirements of about 30 years; many early retirees plan on a lower rate for a longer one.
Why does the savings rate matter so much?
Because it works twice: a higher rate means more invested each year and less spending to replace. Starting from nothing at a 5% real return and a 4% withdrawal rate, saving 10% of take-home pay takes 51 years to reach FI, 30% takes 27 years 8 months, 50% takes 16 years 5 months and 70% takes 8 years 8 months. The size of the income does not change these times, only the share saved.
What is Coast FIRE?
The point where what you have invested will grow to your FI number by a normal retirement age with no more saving. You still work to pay your bills, but you could stop putting money aside. At 35, wanting $50,000 a year from 60 at a 5% real return, the Coast number is $1,250,000 ÷ 1.05²⁵ = $369,128. With $250,000 invested and $30,000 a year going in, you reach it in 4 years 6 months, at 39.
What are Lean FIRE, Fat FIRE and Barista FIRE?
They use the same arithmetic with different spending. Lean FIRE means financial independence on a bare-bones budget: $26,000 a year needs $650,000. Fat FIRE keeps a generous one: $120,000 a year at 3.5% needs $3,428,571. Barista FIRE pays part of your spending from part-time work: $20,000 of part-time pay cuts a $50,000 budget’s FI number from $1,250,000 to $750,000, and in the Barista preset reaches it in 7 years instead of 12 years 8 months.
How do I use the FIRE Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Do I need to install or sign up for anything?
Not at all — it runs in the browser with nothing to install and no account. After it loads once, it even works without an internet connection.
Is my information private?
Yes. Everything happens in your browser. Nothing you type is sent to a server or saved anywhere.
Common Use Cases
Setting a target
Spending $50,000 a year means a $1,250,000 FI number at a 4% withdrawal rate, or $1,428,571 at 3.5%.
Testing a savings rate
Saving half of $100,000 from $80,000 invested reaches FI in 14 years 10 months; saving $60,000 and spending $40,000 takes 11 years.
Lean FIRE
Living on $26,000 of a $65,000 income (a 60% savings rate) reaches a $650,000 FI number in 11 years 3 months, at 39.
Checking Coast FIRE
At 35 with $400,000 invested, the money grows to $1,354,542 by 60 at a 5% real return, past the $1,250,000 needed, so you could stop saving now.
Planning a Barista phase
With $300,000 at 40, $20,000 a year of part-time pay brings financial independence 5 years 8 months sooner than full FIRE.
Last updated: