The entire calculation runs in your browser and in today's dollars: no data is sent to or stored on any server. Because the return is expressed in real terms, you don't need to imagine inflated future numbers.
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The path has two stages, and only one requires saving
Coast FIRE isn't retirement: it's the end of the obligation to set money aside. From that point on you keep working, but only to cover your everyday expenses.
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Depending on the age you stop contributing
The later you stop, the fewer years of compounding your capital has left, and the more capital the plan requires. The row for your current age is highlighted, and the last row is your full FI number.
| If you stop contributing at | Years left to grow | Capital required at that point | Vs. today's number |
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What if the real return isn't what you assume
Here's the fine print of Coast FIRE: the number depends entirely on a return nobody actually knows. A two-point difference changes the result dramatically.
| If the real return were | Multiplier over — years | Coast number today | Vs. your assumption |
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What each figure means
A quick look at every field and every result.
The capital you need invested today so that, without contributing another dollar, it grows on its own to your FI number by the target date. It's the headline figure on this page.
The capital that lets you live off your portfolio: your annual spending divided by the withdrawal rate. With $24,000 in spending and a 4% rate, that's $600,000. It's the final goal, not the Coast number.
The annual return already net of inflation. It's the most delicate assumption of all: the Coast number is a division by (1+r) raised to the years remaining, so changing it moves the result enormously.
The percentage of your capital you withdraw in the first year of independence. The lower it is, the more capital you need, but the more margin you have. To see how it's held up historically, use the safe withdrawal rate simulator.
The situation where you've already surpassed the Coast number: you keep working and covering your expenses, but you don't need to set anything aside. Anything you save from that point on moves the finish line earlier — it doesn't get you there any more surely than you already are.
The entire calculation is expressed in today's purchasing power. Because the return you enter is real, your spending and your capital are compared in the same currency, so you never have to imagine inflated future figures.
How to use this calculator
Steps to use the calculator (expand)
- Your age now: move the slider to your real age. It determines how many years compounding has left to work for you, which is what brings the number down.
- Capital already invested: everything you already have in your portfolio (index funds, retirement accounts, stocks). Don't count your emergency fund or the home you live in — they won't finance your retirement.
- Current annual contribution: what you save and invest per year today. It's only used to tell you how many years you have left to reach Coast; the Coast number itself doesn't depend on it.
- Target retirement age: the age at which you want to be financially independent. Pushing it out a few years drives the Coast number down, because you're giving the capital you already have more time to grow.
- Desired annual spending and withdrawal rate: together they define your FI number (spending divided by rate). 4% is the classic benchmark; for very long horizons it's worth dropping to 3-3.5%. If you want to see how each rate has held up historically, check out the safe withdrawal rate simulator.
- Expected annual real return: already net of inflation. 4-5% is a reasonable assumption for a globally diversified equity portfolio over the long run, but it's an assumption, not a promise. Set it low if you want a demanding, conservative number.
- Read the result in three steps: first the big figure, your Coast number today; then the bar, which tells you what percentage you've already covered and how many years you have left at your current contribution rate; and finally the returns table, to check whether your plan still holds up at 3% instead of 6%.
Frequently asked questions about this calculator
Does reaching Coast FIRE mean I can stop working?
No, and this is the most common mix-up. Coast FIRE is the point where you stop having to save, not the point where you stop having to work. You still need a paycheck to cover your everyday expenses, but you no longer need to set anything aside for the future: the capital you already have invested will grow on its own to your FI number by the target date. It's an intermediate relief that arrives many years before full financial independence.
What real return should I use?
The honest one is the one that feels uncomfortably low. Global equities have historically returned around 5-7% real over very long periods, but that's history, not a promise — and your portfolio isn't the index: it has fees and probably some fixed income. 4-5% is a reasonable assumption for a diversified portfolio, and using 3% gives you a more demanding Coast number, and therefore a plan with more margin if the future disappoints.
Why does the number change so much if I move the return by one point?
Because the calculation divides your FI number by (1 + return) raised to the years remaining, and that exponent amplifies any difference. Over thirty years, going from 4% to 6% nearly cuts the Coast number in half. That's the fine print of this concept: it's not that the calculation is fragile — it's that the result depends entirely on an assumption nobody actually knows. That's why the sensitivity table on this page isn't decoration; it's the important part.
How is this different from the FI number calculator?
That one tells you how much capital you need the day you want to live off your portfolio; this one tells you how much you need today to reach that figure without contributing anything more. They're the same goal seen from two different points in time: the Coast number is your FI number brought back to the present by discounting the real return. If you set your target age equal to your current age, both calculators give exactly the same number.
What if I keep contributing after reaching my Coast number?
Then you'll reach independence before your target date, or with a bigger cushion than planned. Reaching Coast doesn't obligate you to anything — it's an option that opens up. Many people use it to cut back their hours, switch to a lower-paying job they enjoy more, or stop feeling guilty about spending. If you want to see how much sooner you'd get there by keeping up your contributions, use the time to FI calculator.
Does this include inflation and taxes?
Inflation, yes: because the return you enter is real, all figures are in today's dollars, so you don't need to imagine inflated future amounts. Taxes, no. A conservative way to use this tool is to enter the after-tax amount you need as your annual spending, so the Coast number already accounts for that burden.