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Coast FIRE Calculator

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Enter your target retirement spending, age, and expected return to find your Coast FIRE number - the amount you need invested today to coast to financial independence with no further contributions.

Coast FIRE Calculator

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Your Coast FIRE number
$93,662.94
Full FIRE number (at retirement)
$1,000,000
Have you reached it?
Yes - you've reached Coast FIRE
Uses the standard 4% safe withdrawal rate (25x annual spending) for your full FIRE number. Assumes a real (inflation-adjusted) return with zero further contributions.

The formula

FIRE number = Annual retirement spending / 0.04 (the 4% rule, equivalent to x25) Coast FIRE number = FIRE number / (1 + real return rate)^(years until retirement)
Example

Age 30, retiring at 65, planning to spend $40,000/year, 7% real return: FIRE number = 40,000 / 0.04 = $1,000,000. Coast number = 1,000,000 / (1.07)^35 ≈ $93,663 - invest that today, add nothing more, and compounding alone reaches $1M by 65.

Step-by-step guide

  1. Enter your current age and target retirement age.
  2. Enter your planned annual retirement spending and expected real (inflation-adjusted) investment return.
  3. Optionally enter your current invested savings to see if you've already reached your Coast FIRE number.

Why Coast FIRE arrives years before full financial independence

Full FIRE requires accumulating the entire target number through a combination of contributions and growth. Coast FIRE asks a narrower question: given the years remaining before retirement, how much would need to be invested today for growth ALONE to close the entire gap? Because compound growth does most of the heavy lifting over a long enough time horizon, the Coast number is often dramatically smaller than the full FIRE number - which is exactly why many people reach Coast FIRE in their 30s, years or even decades before they'd reach full financial independence through continued saving.

Common mistakes

Using a nominal (non-inflation-adjusted) return rate instead of a real return - this overstates how much your money will actually be worth in today's purchasing power terms.
Treating "reaching Coast FIRE" as meaning you must stop contributing - it simply means you no longer need to, giving you the option to save less, work part-time, or change careers, not an obligation to do so.

Frequently asked questions

What's the difference between Coast FIRE and regular FIRE?

Regular FIRE means you've already accumulated your full target number and can stop working entirely. Coast FIRE means you've saved enough that growth alone will reach that number by retirement age - you still need income to cover current living expenses until then.

Why use a real (inflation-adjusted) return instead of the nominal market average?

Using a real return keeps every number in today's purchasing power, so a $1,000,000 target means the same thing in real terms whether you reach it in 10 years or 35 - avoiding the need to separately guess future inflation.

Does the 4% rule always apply?

It's a widely cited historical rule of thumb based on roughly 30-year retirement horizons, not a guarantee - some planners now suggest a somewhat lower withdrawal rate for extra safety margin, especially for retirements longer than 30 years.

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