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FIRE Number Calculator: How Much to Retire Early?
The number that turns 'someday' into a year.
Financial independence has a surprisingly simple headline number: the amount invested that could fund your spending without a salary. The common shorthand is to divide your annual spending by a safe withdrawal rate — the 4% rule being the famous version, which works out to roughly 25 times what you spend in a year.
Enter your annual spending, what you already have invested and what you add each month. You'll get your target and, more usefully, how long your current pace takes to reach it. Then try the experiment that actually matters: lower your annual spending a little. It shrinks the target and raises what you save — which is why spending moves the date twice as hard as income does.
Good to know
What is a FIRE number?
The amount invested that could cover your yearly spending indefinitely without a salary. It's calculated from what you spend rather than what you earn, which is why two people on the same income can have very different targets.
Is the 4% rule reliable?
It came from historical studies of long retirements and is best treated as a planning shortcut, not a guarantee. Many people use a more cautious rate for very long horizons; lowering the rate raises the target substantially.
Should I use spending before or after retirement changes?
Use what you expect to spend once you're independent, not today's number, if the two genuinely differ — commuting and work costs often fall while health and leisure costs rise.
Why does cutting spending help twice?
Because it lowers the target and raises the amount you can invest at the same time. A permanent reduction in annual spending moves the finish line closer from both directions, which income alone doesn't do.