Financial independence is a number, and the number is the point at which your savings can pay for the rest of your life. Enter what you spend, what you have and what you save — this works out the age the two curves meet.
"Enough" is a choice, not a constant. Each of these is the same calculation against a different standard of living.
| Type | Spending | Corpus needed | Age |
|---|---|---|---|
| Lean FIRE | — | — | — |
| FIRE | — | — | — |
| Fat FIRE | — | — | — |
| Coast FIRE | — | — | — |
Lean is 70% of today's spending, Fat is 150%. Coast FIRE is different in kind: it is the age at which you could stop investing entirely and still drift to a full retirement at 60 on growth alone.
The target climbs because your expenses inflate. Independence is where your corpus catches it. Hover, or focus the chart and use the arrow keys.
An illustration to think with, not a retirement plan or financial advice. Nothing you type is sent anywhere — the whole thing runs in your browser.
Because the 4% rule was derived for a 30-year retirement in a particular market's history, and early retirement is a much longer problem. Someone stopping at 45 and planning to 85 needs their money to last forty years, which is a different question from the one the rule answers.
Working the drawdown out directly also makes the assumptions visible instead of hiding them inside a constant. As it happens, with mainstream inputs the model lands close to 4% anyway — the "first-year withdrawal" figure above shows what rate your own numbers imply, which is a useful sanity check.
The point where you can stop adding money. Your existing corpus, left alone to compound, would reach a normal retirement target by the traditional retirement age on its own. You still have to work to cover your living costs — but not to save. In practice it is the moment the pressure comes off: you can take the less lucrative job, go part-time, or start the thing you actually wanted to do.
It usually arrives many years before full FIRE, which is why it is worth knowing.
Your savings rate, by a wide margin — and it moves the answer from both ends at once. Spending less raises what you invest and lowers the corpus you need, because the target is a multiple of your spending. Try reducing the annual expenses figure by ten per cent and watch how much more the age moves than it does for a one-point change in the return.
The return assumption is the one people fiddle with most and the one they control least.
This page runs one smooth projection from numbers you type in. The Zinfai desktop app runs the same idea against your actual portfolio: real holdings across currencies and jurisdictions, income sources, milestones and debts, bucket strategies, withdrawal simulations, and scenarios side by side — so you are not re-typing your net worth from memory. See how the FIRE engine works.