Calculator
Coast FIRE Number
Coast FIRE is not early retirement. It is the point at which your balance is already big enough to reach your retirement number on its own, with nothing further added, so the savings can stop even though the earning cannot. The arithmetic is one line, and almost every tool that does it gets the units wrong: a 7% return is nominal, a spending target is in today's dollars, and discounting one at the other understates the answer by the whole of inflation compounded over thirty years. This works entirely in real terms and shows you the line you are chasing, which rises every year you have not caught it.
Coast FIRE
Enter what you have invested and what you expect to spend in retirement, then press Calculate.
Where you are now
Invested means invested: every retirement account plus any taxable brokerage earmarked for the same job. Cash in a savings account is not doing the compounding this whole calculation depends on, and counting it overstates the answer.
Contributions should include your employer's match, because it lands in the same account and compounds the same way. It is the figure you would stop adding on the day you started coasting.
Every account, added together. Cash doesn't count.
Yours plus any employer match
Today
When you'd draw on it
What you're aiming at
Spending is in today's dollars — what that life would cost if you were living it this year. Do not inflate it yourself; the calculation handles that.
Other income — a pension, Social Security, an annuity — is money the portfolio does not have to produce, so it comes straight off the target and reduces the coast number in proportion. Leave it at zero if you would rather not count on it.
Return and inflation are entered separately on purpose. The gap between them is the only rate that matters here, and quoting a nominal return against a target in today's dollars is the single most common way this calculation goes wrong.
In today's dollars — what that year would cost now
Pension, Social Security
4% by convention
Nominal, before inflation
Long-run average is about 3%
Coasting is not retiring. It means you can stop saving — you still have to earn enough to cover what you spend between now and then.
For educational purposes only. Results are estimates and do not constitute financial, tax, or legal advice. Consult a qualified professional before making any financial decisions.
How to use it
Invested means invested. Every retirement account plus any brokerage balance earmarked for the same job, added together. Cash in a savings account is not doing the compounding this whole calculation rests on, and counting it will tell you that you are further along than you are.
Spending goes in as today's money — what that life would cost if you were living it this year. Do not inflate it yourself. The calculation handles inflation, and doing it twice is the most common way people end up with a target they will never reach.
If you expect a pension or intend to count on Social Security, put it in other retirement income. It comes straight off what the portfolio has to produce, and it moves the coast number more than almost any other input.
Press Example to load a worked case: a 32-year-old with $180,000 invested, adding $24,000 a year, aiming at $70,000 of spending at 65.
The units mistake that runs through this genre
Almost every coast calculator asks for a 7% return and a spending target in today's dollars, then divides one by the other. Those two figures are in different units. 7% is nominal — it includes inflation. Today's dollars are real.
Discounting a real target at a nominal rate understates the coast number by the whole of inflation compounded over the horizon. Over thirty years at 3%, that is a coast number roughly 60% too low. The error always runs the same direction: it tells you that you can stop saving when you cannot.
This tool converts the return to a real one — precisely, as (1 + return) ÷ (1 + inflation) − 1, not by subtracting — and prints the result on the results card. Every dollar on the page is a today's dollar. If a figure here looks higher than one you have seen elsewhere, this is why.
Coasting is not retiring
Reaching the number means the saving can stop. The earning cannot. You still have to cover rent, food, and insurance between now and the retirement date you entered, and the projection assumes you never touch the balance in the meantime — one withdrawal to cover a gap year sets the whole thing back.
What it buys is optionality. Somebody saving a third of their income who reaches this point can take a job that pays a third less without changing their retirement at all. That is the entire proposition, and it is a large one.
The coast number is also not a finish line you cross once. Spend more in retirement than you planned, retire earlier, or live through a decade of poor returns and you are behind it again. It is worth re-checking against a real balance about once a year, which is what the printable table is for.
Assumptions and limits
- A single average return is not a market. Sequence-of-returns risk — a bad decade arriving early rather than late — changes the outcome materially, and no fixed-rate projection of any kind can capture it. Treat the answer as a central case, not a forecast.
- The retirement number is spending, less other income, divided by the withdrawal rate. The 4% convention comes from a study of 30-year US retirements; a longer retirement, a different asset mix, or worse valuations at the start all argue for less.
- Taxes are not modeled. The balance is treated as one pot, where a dollar in a traditional 401(k), a Roth, and a brokerage account are worth different amounts at withdrawal — and that mix decides how much of the number you actually spend.
- Other retirement income is assumed to start at the retirement age you entered and to keep pace with inflation. Social Security does the second; it does not necessarily do the first, and claiming early reduces it permanently.
- An estimate for planning. Not financial advice.