Having enough invested that compounding alone reaches your FIRE number by your target retirement age. You still work to cover today’s living costs, but you no longer need to save for retirement from that income.

How is the Coast FIRE number calculated?

Take your full FIRE number — annual spending divided by your withdrawal rate — and divide it by (1 + real return) raised to the number of years until your target retirement age.

Does reaching Coast FIRE mean I can quit my job?

No. It means retirement savings are handled; your income still has to cover current spending. What it buys is flexibility — a lower-paid job, fewer hours, a career change or a sabbatical, without derailing the retirement plan.

Which return should I assume?

Enter a real return, after inflation. A diversified equity-heavy portfolio has historically returned roughly 5–7% real over long periods, but the sequence matters enormously over a single lifetime, so it is worth checking how your number moves at 4% and at 6% before relying on it.

Does it matter whether the money is in a 401(k) or a brokerage account?

Not for the coast calculation, which only cares about the total invested and the real return on it. It matters a great deal at withdrawal: money in a 401(k) or traditional IRA is taxed as income on the way out, Roth balances are not, and early access rules differ.

Coast FIRE Calculator — Find Your Stop-Saving Age

Your balance if you never invest another dollar

What today’s invested balance grows into on its own, with every future contribution switched off. This is the projection Coast FIRE is a claim about.

Growth of $120,000 at a 5% real return with no further contributions, against a FIRE number of $1,500,000.
Age	Balance	Share of FIRE number
Age 32	$120,000	8%
Age 35	$138,915	9%
Age 38	$160,811	11%
Age 41	$186,159	12%
Age 44	$215,503	14%
Age 47	$249,471	17%
Age 50	$288,794	19%
Age 53	$334,316	22%
Age 56	$387,012	26%
Age 59	$448,015	30%
Age 62	$518,633	35%
Age 65	$600,383	40%

Real (after-inflation) returns, so every figure is in today’s dollars. Contributions are set to zero for the whole projection — this is deliberately the pessimistic case.

Your Coast FIRE number is your full FIRE number discounted back to today — always smaller, and much smaller the younger you are.
Reaching it does not mean you can stop working; it means you can stop saving for retirement specifically.
Coast FIRE is meaningless without a target age — the same balance coasts for a 30-year-old and does not for a 55-year-old.
Once you are coasting, every further dollar invested buys an earlier retirement rather than a possible one.

How the Coast FIRE calculator works

Coast FIRE is the point where you have enough invested that compounding alone will carry you to financial independence by your target retirement age. You still need an income to cover your living costs, but you no longer need to save for retirement out of it.

The calculator works backwards. It takes the full FIRE number you would need at retirement — annual spending divided by your withdrawal rate — and discounts it back to today at your expected real return. That discounted figure is your Coast FIRE number, and it is always smaller than the full one, by a factor that grows the further away retirement is.

The age fields are what make this page different from the plain FIRE calculator. Coast FIRE has no meaning without a deadline: the same balance that comfortably coasts a 30-year-old is nowhere near enough for a 55-year-old, because it has 25 fewer years to compound.

The math

Full FIRE number = annual spending ÷ withdrawal rate. Coast FIRE number = full FIRE number ÷ (1 + r)^n, where r is your expected real return and n is the years between your age now and your target retirement age.

The 4% withdrawal rate offered here comes from the Trinity study, which tested historical US market data over 30-year retirements. It is a rule of thumb and not a guarantee — a longer retirement, a different asset mix or a bad opening decade all change the answer, which is why 3% and 3.5% are offered alongside it.

Returns are entered as real returns, meaning after inflation, so every number on the page is in today’s dollars and no separate inflation adjustment is applied. The "could stop contributing at" figure is found by stepping forward month by month until your projected balance first covers the shrinking coast requirement — there is no closed form for it, because the balance is compounding and receiving contributions while the requirement compounds on its own.

Worked example

A 32-year-old planning to spend $60,000 a year from age 65 needs a full FIRE number of $1,500,000 at a 4% withdrawal rate. Discounted back 33 years at a 5% real return, the Coast FIRE number is about $299,800.

With $120,000 invested today they are roughly $179,800 short of coasting, and that $120,000 left completely alone would reach about $600,400 by 65 — 40% of the target. Adding $18,000 a year, they cross the coast line at about age 46. From then on, contributing is optional: stopping entirely still lands them at $1,500,000 by 65, and anything they do keep adding buys an earlier retirement instead.

Key terms

Coast FIRE number: The invested balance that grows into your full FIRE number by your target retirement age with no further contributions.
Real return: Investment return after inflation. Using a real return keeps every projection in today’s dollars, so a future balance means what it sounds like it means.
Coast point: The age at which your balance first covers the coast requirement, given the contributions you are still making. After it, contributing becomes optional.
Full FIRE number: The portfolio that funds your spending indefinitely at your chosen withdrawal rate — annual spending divided by that rate, or 25× at 4%.

Coast FIRE Calculator (US, 2026)