Calculator
FIRE Calculator
FIRE is financial independence, retire early — the point where what you've invested can pay for your life. This page turns the spending you'd want covered into your FI number, checks whether what you have already would grow to it on its own by your target age (Coast FIRE), and counts the years to get there on what you save now. On $50,000 a year of spending, $60,000 invested and $1,500 a month at 5%, the FI number is $1,250,000, the Coast FIRE number today is about $289,222, and the current path reaches FI in 27 years 3 months, at age 57.
How this works
Two numbers do the work here, and the second is always smaller than the first. The FI number is the invested balance that can pay for a year of your life without being used up: your annual spending divided by the withdrawal rate. At 4%, that is 25 times spending — $50,000 a year needs $1,250,000, because 4% of $1,250,000 is $50,000. Set the rate lower and the number grows: 3% is about 33 times spending.
The Coast FIRE number is the same target seen from today: the amount that, invested now and never added to, would grow into the FI number by your target age on its own. It is the FI number shrunk back by the years of growth still ahead — at 5% a year over 30 years, money multiplies by about 4.32 (1.05 raised to the 30th power), so the $1,250,000 target shrinks to about $289,222 in today's balance. "Coast" means exactly that: someone at the coast number could stop contributing, cover only today's bills from their income, and still arrive. Nothing on this page suggests doing so; it only tells you where the line is. The further away your target age, the smaller the coast number, which is why the same $300,000 can be past it at 30 and far short of it at 45 — about $289,000 is enough with 30 years to go, while 15 years to go needs about $601,000.
The years to FI line runs your current path month by month: the balance grows at the return (compounded monthly at the rate that makes twelve months add up to exactly the annual return, not the annual rate divided by twelve), your contribution lands at the end of each month, and the count stops the first month the balance reaches the FI number. The Coast FIRE age is found on the same walk, against a moving target: each year you get closer to the target age, the coast number for that year rises (less growth left to do the work), while your balance rises too, and the coast age is the age at which the balance first catches the requirement. It is never reached later than FI itself, because at the target age the two numbers are the same.
A worked example
Take the defaults: 30 years old, aiming at 60, with $50,000 a year of spending to cover, $60,000 invested and $1,500 going in each month, at a 5% return after inflation and a 4% withdrawal rate. The FI number is $1,250,000.00. The Coast FIRE number today is $289,221.81 — left alone for 30 years at 5%, that grows to the FI number. $60,000 is $229,221.81 short of it; left alone, $60,000 would reach about $259,317 by 60, a fifth of the target. Keep contributing $1,500 a month and the path crosses the coast line at age 50, when the balance is about $767,905 against a coast number of about $767,392 for that year, and reaches the FI number itself in 27 years 3 months, at age 57. Carry on to 60 and the balance is about $1,482,380. The chart draws that path against the flat FI line; where they meet is the answer.
Common questions
Is the 4% rule safe? It is a finding, not a promise. The rule comes from the Trinity study (Cooley, Hubbard and Walz, 1998), which looked at U.S. stock and bond returns and found that a retiree who withdrew 4% of a stock-heavy portfolio in the first year, then raised that dollar amount with inflation, had very rarely run out within 30 years. So it describes the past, over 30-year spans, for mixed portfolios — it was not built for a retirement of 40 or 50 years, and it says nothing about your taxes or fees. People who want more margin plan on a lower rate and a bigger number: at 3.5%, the FI number for $50,000 of spending is $1,428,571.43 instead of $1,250,000.00; at 3% it is $1,666,666.67. This page lets you set the rate; it does not pick one for you.
What return should I assume? One after inflation, because the spending you typed is in today's dollars and the FI number has to buy today's life, not the life of 2056. A diversified stock-heavy portfolio has historically returned something like 7% a year after inflation over long stretches; 5% is a common planning figure that leaves room for a worse run. It is the input that moves the answer most: on the defaults, 5% reaches FI in 27 years 3 months, 7% in 22 years 9 months, and 3% in 34 years 8 months. The honest use of this page is to try more than one.
Do I count my house? Not here. The FI number is the pile that pays for your life, so only money that can be drawn down without selling the roof over your head belongs in it — stocks, bonds, retirement accounts, cash set aside for this. Your home is part of your net worth and worth tracking there, and a paid-off one lowers the spending you need covered, which shrinks the FI number from the other side. The net worth calculator keeps the full picture, house included.
This is arithmetic on your assumptions, not a forecast. It leaves out taxes on withdrawals, Social Security or a pension, the order in which good and bad market years arrive (sequence risk — the same average return can end very differently depending on when the bad years land), fees, and any change to your spending or income. All of those are left out on purpose so the three numbers stay readable; a plan that depends on them needs more than a page like this.