Coast FIRE calculator

Coast FIRE is the point where your existing investments, left completely alone, would reach your retirement number on their own. After that, you only have to cover today's living costs.

The calculator

Coast FIRE number$347,066What you need invested today
Retirement target$1,500,00025× annual spending
Still needed$197,066To reach Coast FIRE today
Your investments at retirement$648,291If you never contributed another dollar for 30 years

You are $197,066 short of Coast FIRE. At 5.0% real over 30 years, you would need $347,066 invested today for compounding alone to reach $1,500,000.

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How the number is worked out

Two steps. First the retirement target: annual spending divided by the withdrawal rate. At 4% that is 25 times spending, at 3.5% about 29 times. Then the target is discounted back to today at the real return, over the years remaining until retirement.

In formula terms, the Coast FIRE number is the target divided by (1 + r)n, where r is the real return and n is years to retirement. With the defaults above, a $1,500,000 target discounted over 30 years at 5.0% comes back to $347,066.

Because the calculation is done in real terms, you can compare the answer directly with what you spend today. No inflation adjustment is needed at the end, which is precisely why working in real terms is worth the small extra care up front. See real return for why nominal figures mislead over long horizons.

What it assumes, and where that breaks

It assumes one constant real return every year for the whole period. Markets do not do that, and the difference is not a rounding error: the same average return delivered in a different order produces materially different outcomes once you start withdrawing. That is sequence of returns risk, and no single-path calculator can show it.

It also assumes your spending target is right, that the withdrawal rate is sustainable over your actual horizon, and that you pay no fees. On that last point: a 1% annual fee reduces a 6% real return to roughly 5%, which over thirty years changes the Coast FIRE number by a large margin. The investment fee calculator will size that.

For an early retirement in particular, the withdrawal rate deserves more scrutiny than a calculator can give it. The 4% figure was derived from 30-year windows; a retirement starting at 45 may run fifty years. The FIRE planning guide covers what changes at that horizon.

Frequently asked questions

What is Coast FIRE?
The point at which your existing invested savings, with no further contributions, would grow to your retirement target by your chosen retirement age.
What real return should I assume?
Between 4% and 6% after inflation is a common range for a diversified equity-heavy portfolio. The result is very sensitive to this number, which is why a simulation that models a range of outcomes is more informative than any single assumption.
Does reaching Coast FIRE mean I can stop working?
No. It means you can stop saving for retirement specifically. You still need income to cover current living costs until you retire.
Read the FIRE planning guideSimulate the whole plan