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FI number calculator
The portfolio that makes work optional — your annual spending divided by a safe withdrawal rate. Below you'll get the number, the year you're on track to reach it, and an honest look at how much the whole thing hinges on one assumption.
Your FI number
$1,250,000
$50,000 of annual spending at a 4% withdrawal rate — that's 25× your yearly costs. You've banked 3.0× so far.
You're at 12% — $1,100,000 to go.
On these assumptions you reach it in 19.2 years — around 2045, at age 54.
Another $500/month would pull that forward by 2.0 years — to 17.2 years from now.
If the withdrawal rate isn't 4%
| Rate | FI number | Time to reach |
|---|---|---|
| 3.0% | $1.67M | 22.8 yrs |
| 3.5% | $1.43M | 20.8 yrs |
| 4.0%← | $1.25M | 19.2 yrs |
| 4.5% | $1.11M | 17.8 yrs |
| 5.0% | $1M | 16.5 yrs |
Dropping from 4% to 3% raises the target by a third and adds years. The 4% rule came from a specific study of 30-year US retirements — it's a reasonable anchor, not a guarantee, and a longer retirement argues for a lower rate.
Your number only means something in motion. Spending changes, markets move, and the gap closes quarter by quarter. Fuego keeps the whole line — free, and without ever linking your bank.
Track your progressEverything is in today's money — returns are real (after inflation), so the figures stay comparable to what you spend now. Taxes, healthcare and one-off costs aren't modelled. For education, not financial advice.
The number is easy. The assumption underneath it isn't.
Every FI number is one division: spending ÷ withdrawal rate. Spend $50,000 a year, use 4%, and you need $1.25M. That much is arithmetic, and it's why nearly every calculator on the internet stops right there.
The interesting question is how much weight that one rate is carrying. Move it from 4% to 3% — a change most people would call cautious rather than dramatic — and the same $50,000 lifestyle needs $1.67M instead. You just added $417,000 and probably several years, without changing anything about how you actually want to live. That's why the table above shows the spread rather than a single confident figure.
What the 25× figure quietly assumes
- A 30-year retirement. That was the test the 4% rule was built against. Retiring at 45 asks the portfolio to last far longer, which argues for a lower rate.
- Historical US returns. Among the strongest any market has produced. Assuming they repeat is a choice, not a certainty.
- Spending that holds steady. Real retirements are lumpy — a roof, a car, a medical year. Flexibility to cut back in bad markets is worth more than a slightly bigger number.
- Spending that includes everything. Tax on withdrawals and health cover are living costs. If they aren't in your spending figure, your target is too low.
Why your house isn't in this number
A withdrawal rate is a statement about assets you can sell down to pay yourself. The home you live in isn't one of them — it may be your single largest asset and it still never sends you a paycheque unless you sell it and move somewhere cheaper. Adding it to the portfolio side of a 4%-rule calculation makes you look closer to FI than you are.
Owning it outright still helps enormously — it lowers the spending your FI number has to cover, which shrinks the target from the other direction. That's the honest way it enters the maths. Fuego draws this line everywhere in the app, calling the assets that can genuinely fund a paycheque the withdrawable engine.
Common questions
- What is my FI number?
- Your FI number is the size of portfolio that can fund your living costs indefinitely from withdrawals rather than work. It's your planned annual spending divided by a safe withdrawal rate — at 4%, that's 25 times your yearly spending. Reaching it is what people mean by financial independence: work becomes optional rather than required.
- Where does the 4% rule come from, and can I trust it?
- It comes from the Trinity study and William Bengen's work in the 1990s, which looked at historical US market data and asked what withdrawal rate survived a 30-year retirement. 4% held up in nearly every historical window. Two caveats matter: it was built around a 30-year horizon, so a retirement starting at 40 is a longer test; and it rests on historical US returns, which are among the best any market produced. Treat 4% as a well-researched anchor, not a law — many people retiring early prefer 3.25–3.5%.
- Should I count my house in my FI number?
- No — this calculator counts invested assets only. A withdrawal rate describes a portfolio you can actually sell down to pay yourself, and the home you live in can't do that without you moving. Owning it outright reduces the spending your FI number has to cover, which helps enormously, but it isn't part of the portfolio itself. Fuego makes the same split throughout the app, calling the assets that can genuinely fund a paycheque the withdrawable engine.
- Does the FI number account for taxes and healthcare?
- Not directly, and no simple calculator's does. The clean way to handle both is to put them in your spending figure: if you'll owe tax on withdrawals or pay insurance premiums, those are living costs, so raise your annual spending until it reflects the real total. A number built on pre-tax spending will quietly understate the target.
- What's the difference between the FI number and Coast FIRE?
- The FI number is the finish line — enough invested to cover your spending. Coast FIRE is the earlier point where what you've already invested will grow into the FI number by your target retirement age, so you can stop saving for retirement even though you still work. Coast FIRE almost always arrives first, and there's a separate calculator for it here.
Related
Reaching your FI number is the finish line. The earlier milestone — where what you've already invested will get there on its own, so you can stop saving for retirement — is Coast FIRE. Try the Coast FIRE calculator →
Watch the gap close
A calculator answers for today. Fuego keeps the whole line — one quiet update a quarter, your FI progress and projected date redrawn each time. Free forever, and it never asks for your bank login.
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