Calculate your Coast FIRE number — how much to invest today so compound growth reaches your retirement target without further contributions.
Added Jun 16, 2026
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Enter a value for annual expenses in retirement to see your result.
Coast FIRE is the point where your current investments will grow to your full FIRE number by retirement — without any additional contributions. Once you reach your Coast number, you only need to cover living expenses, not save for retirement.
Coast Number = FIRE Number ÷ (1 + r)^n
To spend $50k/year in retirement at a 4% withdrawal rate, you need $1.25M. At 7% annual return over 35 years, you need only ~$117k invested today — it will grow to $1.25M by age 65 without further contributions.
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Coast FIRE is the point where your invested savings will grow to your full FIRE number (retirement portfolio target) by your target retirement age — without any additional contributions. Once you hit your Coast number, you only need to earn enough to cover current living expenses.
Regular FIRE means your portfolio is already large enough to retire now. Coast FIRE means your portfolio is large enough that, given time and compound growth, it will reach the regular FIRE number by retirement — but you haven't retired yet. Coast FIRErs typically work just enough to cover expenses, not save for retirement.
The US stock market has returned roughly 10% nominal and 7% real (inflation-adjusted) over long periods. Using 7% (real) gives a conservative estimate. For a nominal projection, use 9–10% and remember the final portfolio will need to be discounted for inflation.
If your current portfolio exceeds your Coast FIRE number, you are already coasting. Your investments will grow to your full retirement target without any further contributions. You only need to cover your current living expenses until retirement.