Coast FIRE calculator

How Coast FIRE actually works

Most retirement maths asks one question: how much do I need at the end? Coast FIRE asks a better one for people in the middle of their working life — how much do I need right now, so that the end takes care of itself?

The logic runs in two steps. Your FI number is the portfolio that can fund your retirement spending at a safe withdrawal rate — at 4%, that's 25× your annual spending. Then you discount that number backwards to today at your expected real return. Whatever is left is the amount that compounding alone can carry across the finish line.

The consequence is the interesting part. Reaching Coast FIRE doesn't mean you can stop working — you still need to cover today's bills. It means you can stop saving for retirement. Every dollar after that is a choice: retire earlier, retire richer, or simply take a job you like more for less money.

The part most calculators leave out: the target moves

Your Coast FIRE number isn't fixed — it rises every year. It has to, because it's the FI number discounted over your remaining runway, and that runway gets one year shorter each birthday. At 35 with 25 years to go you need about $230,000; wait until 45 and the same plan needs roughly $453,000. Delay is expensive in a way a single static number hides.

Which leads to a conclusion worth sitting with: if you stop contributing before you reach Coast FIRE, you never reach it. Your portfolio compounds at your expected return — but so does the target, at exactly the same rate. The two move in lockstep, so the percentage never budges. Coasting keeps you where you are; only contributions close the gap. Set the monthly contribution above to 0 and watch the calculator say so.

Why this one ignores your house

Plenty of calculators let you type your whole net worth into the box. That quietly flatters the answer. A safe withdrawal rate is a statement about a portfolio you can actually sell down to pay yourself — and the home you live in isn't that. It may well be your largest asset, and it still won't send you a paycheque in retirement unless you sell it and move.

So this calculator asks only for invested assets. Fuego draws the same line everywhere in the app, where the assets that can genuinely fund a 4%-rule paycheque are called the withdrawable engine — separate from stored value like a house or a car. It's a less generous number, and a more honest one.

Common questions

What is Coast FIRE?

Coast FIRE is the point where the money you've already invested will grow to your full financial-independence number by your target retirement age — even if you never contribute another dollar. You still need income to cover today's expenses, but you no longer have to save for retirement. Everything after that is optional, and buys you either an earlier or a richer retirement.

How is the Coast FIRE number calculated?

First your FI number: annual retirement spending divided by your safe withdrawal rate — 4% gives the familiar 25× figure. Then that number is discounted backwards to today at your expected real return, over the years between your age now and your target age. In short: Coast FIRE = FI number ÷ (1 + real return) ^ years remaining.

Does my Coast FIRE number change over time?

Yes, and it goes up. The number is your FI target discounted over the years left before retirement, so every year of runway you use makes the amount you'd need today larger. There's a sharp consequence: if you stop contributing while you're still short of Coast FIRE, you never get there. Your portfolio compounds at your expected return, but the target rises at exactly the same rate, so the gap stays proportionally identical forever. Coasting holds your position; only contributions close the gap.

Should I include my house?

No. This calculator counts invested assets only — brokerage, retirement accounts, and anything else that compounds and can eventually pay you. The home you live in grows in value but never sends you a cheque, so counting it in a withdrawal-rate calculation quietly overstates how close you are. That distinction is the same one Fuego makes throughout the app, where it's called the withdrawable engine.

What return should I use?

The default here is 7% real, meaning after inflation. This is deliberately the assumption to argue with: it's the single input your result is most sensitive to, and a couple of percentage points either way moves the answer a lot. Try a pessimistic number as well as a hopeful one and see how much the range changes.

Is Coast FIRE the same as being financially independent?

No — they're different milestones. Coast FIRE means your retirement is on autopilot; financial independence means your investments can actually cover your living costs now. Coast FIRE almost always arrives first, and it's the point where most people feel their working life get meaningfully less tense.