Financial independence: the nest egg that lets your investments cover your spending, and how far off it is.
A FIRE calculator estimates your financial-independence number, the nest egg that lets your investments cover your spending, and how many years of saving it will take to get there.
The FIRE number is usually your annual spending divided by a safe withdrawal rate. At the common 4% rate, that's 25 times what you spend in a year, the level at which a diversified portfolio has historically funded roughly 30 years of inflation-adjusted withdrawals. Spend less or choose a more conservative 3.5% rate and the multiple rises.
How soon you reach independence depends far more on the share of income you save than on how much you earn. A high savings rate does double duty: it grows the portfolio faster and lowers the spending the portfolio must cover, pulling the target down. That's why frugality and income both matter, but the savings rate is what actually sets the timeline.
The invested savings at which your withdrawals cover your spending indefinitely, usually your annual spending divided by your withdrawal rate (25× spending at 4%).
A guideline that you can withdraw about 4% of your portfolio in year one, adjust for inflation after, and expect it to last ~30 years. Lower rates are more conservative.
It depends on your savings rate. The higher the share of income you invest, the sooner you reach independence, the math rewards a high savings rate more than a high income.
See the exact formula and a worked example on our methodology page.