Coast FIRE Calculator

Coast FIRE is a variation of the FIRE (Financial Independence, Retire Early) movement that focuses on a specific milestone: having enough invested that compound growth alone will reach your FIRE number by traditional retirement age — without any additional contributions. Once you've "coasted," you only need to earn enough to cover your current living expenses, not save for retirement.

The Coast FIRE calculation: determine your FIRE number (annual retirement expenses ÷ safe withdrawal rate). Then work backward using your expected real (inflation-adjusted) investment return to find how much you'd need invested today for compound growth to reach that number by a target age.

Example: You want $1,000,000 at age 65. You're 35 today — 30 years of growth. At 7% real return: $1,000,000 ÷ (1.07)^30 = $131,367. If you have $131,367 invested at 35, you've Coast FIRED — compound growth alone gets you to $1M by 65, even if you never contribute another dollar.

The appeal of Coast FIRE: it allows a much lower-pressure working life. Once you've reached your Coast number, you can: switch to a lower-paying but more meaningful career, go part-time, take a sabbatical, move to a lower cost-of-living area, or pursue entrepreneurial risks without retirement anxiety. The traditional FIRE path requires continued aggressive saving for years or decades — Coast FIRE lets you ease up much earlier.

Coast FIRE is most achievable for people who start investing aggressively in their 20s. Starting at 22 with $1,000/month at 7% return, you'd reach the Coast number for a $1M FIRE target ($253K) by age 31. The same person starting at 32 would need to invest until 40 before coasting.