FIRE calculator
Three numbers give you the year work becomes optional and the balance you will need. Add your age and it gives you the age too.
- 1 Your numbers
- 2 Your date
How to read it
Take Priya, the example in the empty form above. She is 35, has $200,000 invested, adds $2,500 a month, and lives on $4,000 a month. Her FIRE number is $1,200,000, which is 25 times $48,000 a year. At her current pace she reaches it in 15 years, in 2041, at 50. After that her investments can pay for her life without a paycheck, and work becomes a choice.
The year is an estimate, not a promise. It assumes she keeps investing $2,500 a month and her spending stays where it is in today's dollars. Invest more and the year comes sooner. Spend less and the whole target drops, so the year comes sooner. Rerun it once a year with your real balance.
The calculator counts whole years. A balance that reaches the number part way through a year prints as that year. It does not print a month, because it does not compute one.
A raise moves the year only if you invest it. The line under the year takes a $10,000 raise, keeps 70% of it after tax, and adds that to your monthly investing with spending held flat. For Priya that is $583 a month more, and it moves her year from 2041 to 2039. Most FIRE calculators leave the raise out, and it is the one lever with no ceiling.
The math
FIRE number = 25 × yearly spending
each year, balance = balance × 1.07 + 12 × monthly investing
your year = the first year the balance reaches the FIRE number
Start with what you spend in a year. Multiply by 25. That is the 4% rule written as a target. A portfolio that pays out 4% of its starting value each year, adjusted for inflation, has lasted 30 years or longer in most historical periods, not all. Twenty-five times spending is the same number written the other way around. Priya spends $48,000 a year, so her number is $1,200,000.
Then grow the balance one year at a time. Each year it grows by 7% and twelve months of investing go in. Priya starts at $200,000. After one year she has $244,000. After 15 years the balance passes $1,200,000, and that is her year.
The 7% is a real return, meaning after inflation. It is close to what a broad stock index has averaged after inflation over long stretches. Using a real return means every figure on this page is in today's dollars. Her $4,000 a month of spending stays $4,000 a month, and the target stays $1,200,000, with no inflation math to do in your head.
The raise line takes a gross yearly raise and keeps 70% of it. Tax takes the other 30%, our standing assumption for someone in the 22% federal bracket plus 7.65% for Social Security and Medicare, rounded up. What is left is divided by 12 and added to your monthly investing, with your spending held flat.
What the calculator assumes
- Growth is 7% a year after inflation, every year, with no losing years. Real markets do not move in a straight line, and the order of returns matters. Treat the result as a pace, and rerun it once a year.
- Spending is what you will live on, in today's dollars. The fun is included. Leave out what you save and invest, one-time goals, and debt payments that end before your date.
- The FIRE number is 25 times spending, which is a 4% withdrawal rate. For a retirement longer than 30 years, use 28 or 30 times.
- What you invest each month stays the same every month until the year arrives. A raise you invest is the one change the page models, on the line under the year.
- The raise keeps 70% after tax. State income tax is not in that number. If your state taxes income, you keep a little less than the line shows.
- No Social Security or pension is counted. Either one lowers the target, so if you expect one your number is lower and your year is earlier than the page shows. The app counts both.
- Your age is added to the whole years it takes.
Your FIRE number by monthly spending
Find the row closest to your monthly spending. The FIRE number is 25 times a year of that spending. It is the balance the 4% rule says can pay for that spending, for 30 years or longer in most historical periods.
| Monthly spending | Yearly spending | FIRE number |
|---|---|---|
| $3,000 | $36,000 | $900,000 |
| $4,000 | $48,000 | $1,200,000 |
| $5,000 | $60,000 | $1,500,000 |
| $6,000 | $72,000 | $1,800,000 |
| $8,000 | $96,000 | $2,400,000 |
How many years it takes from zero
This table starts from nothing invested and grows at 7% a year. Find what you invest each month down the side and your monthly spending across the top. Each cell is the number of years. If you already have a balance, your year is earlier, and the tool above counts it.
| Each month | $3,000 | $4,000 | $5,000 | $6,000 |
|---|---|---|---|---|
| $500 | 37 | 41 | 44 | 46 |
| $1,000 | 28 | 31 | 34 | 37 |
| $1,500 | 23 | 26 | 29 | 31 |
| $2,000 | 20 | 23 | 25 | 28 |
| $3,000 | 15 | 18 | 21 | 23 |
Read across a row and the years grow with spending, because the target does. Read down a column and they fall, because more goes in every year and the growth works on a bigger balance.
Questions people ask
What is a FIRE calculator?
A FIRE calculator tells you when you could stop working for money. FIRE stands for financial independence, retire early. You type what you have invested, what you add each month and what you spend. The calculator grows the balance year by year until it reaches 25 times your yearly spending, and reports that year.
What is my FIRE number?
Your FIRE number is 25 times what you spend in a year. Spend $4,000 a month and the number is $1,200,000. Spend $6,000 a month and it is $1,800,000. It is the balance that can pay you 4% a year, which is the spending you typed. The book calls it your FI Number. It is the same figure.
How is the year calculated?
The calculator starts with your invested balance. Each year it grows the balance by 7% and adds twelve months of your investing. The first year the balance reaches your FIRE number is your year. It counts whole years, so a date that falls part way through a year prints as the year it completes.
Why 7% growth?
7% is a real return, which means after inflation. It is close to what a broad stock index has averaged after inflation over long stretches. Using a real return keeps every figure in today's dollars, so your spending and your FIRE number do not need an inflation adjustment.
Why 25 times spending?
25 times spending is the 4% rule written as a target. A portfolio that pays out 4% of its starting value each year, adjusted for inflation, has lasted 30 years or longer in most historical periods, not all. If your retirement will run longer than 30 years, a bigger multiple such as 28 or 30 is safer.
Does the calculator include Social Security or a pension?
No. It uses your spending and your investing only. Guaranteed income lowers the target, so if you expect a pension or Social Security your real number is lower than the one shown, and your year is earlier. The app takes both into account.
What does a raise do to the year?
A raise moves the year only if you invest it. The calculator keeps 70% of a raise, since tax takes about 30%, and adds that to your monthly investing with spending held flat. How far it moves depends on how far out you are. Early on, a $10,000 raise invested this way can move the year by several years. Close to your number it may move the year by less than a year, and the calculator then shows no change.
What is the difference between this and the coast FIRE calculator?
This calculator finds the year your investments can cover all of your spending. The coast FIRE calculator finds the smaller balance that will grow into that amount by a retirement age with no more contributions. You reach coast FIRE first and full FIRE later.