... LIVE
Enter your current age (18โ€“70)
Must be greater than current age
$
Enter current savings
$
How much you need per year in retirement Enter annual retirement spending
%
7% is a common inflation-adjusted estimate
%
4% is the classic FIRE rule
YOUR COAST FI NUMBER
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FIRE Number
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needed at retirement
Coast Status
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Current Portfolio
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vs coast number
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What Is Coast FI (CoastFIRE)?

Coast FI is a milestone in the FIRE (Financial Independence, Retire Early) journey. When you hit your Coast FI number, your existing investments will grow to your full retirement goal without any additional contributions, thanks to compound growth.

Coast FI = FIRE Number รท (1 + r)^years
FIRE Number = Annual Spending รท SWR. Years = retirement age โˆ’ current age. r = expected annual return. Example: $1.5M FIRE number at 7% over 35 years = ~$184,000 Coast FI.
๐Ÿ’ก Once you hit Coast FI, you only need to earn enough to cover current living expenses โ€” you can stop contributing to retirement accounts entirely.

Frequently Asked Questions

Regular FIRE means you have enough to retire now. Coast FI means you have enough saved that future compound growth will fund retirement โ€” but you still need income for current living expenses until retirement age.

You do not have to, but mathematically your existing savings will grow to your goal without new contributions. Many people at Coast FI continue investing to reach full FIRE sooner, or redirect savings to other goals.

7% is commonly used as the inflation-adjusted historical average for a diversified index fund portfolio. The S&P 500 has averaged about 10% nominal, or ~7% real (after inflation). Conservative planners use 5โ€“6%.

The 4% rule says you can withdraw 4% of your portfolio annually and not run out of money over 30 years. If you spend $60,000/year, you need $1,500,000 saved. It comes from the Trinity Study (1998).

Congratulations โ€” you have already reached Coast FI! Your existing portfolio will grow to your FIRE number by retirement at the assumed return rate, with no additional contributions needed.

This calculator does not include Social Security. To get a more accurate number, subtract your expected annual SS benefit from your retirement spending before entering it.

Sources & Methodology
Uses standard compound growth mathematics and the 4% safe withdrawal rate from the Trinity Study.
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Trinity Study โ€” Cooley, Hubbard & Walz (1998)
Foundational research establishing the 4% safe withdrawal rate for 30-year retirement periods
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Vanguard โ€” Long-Term Stock Market Returns
Historical S&P 500 data supporting the 7% inflation-adjusted annual return assumption
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FIRE Community โ€” Coast FI Framework
Compound growth milestone framework popularized in the financial independence community
Last updated: March 2026
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