Coast FIRE Calculator

Coast FIRE is a milestone on the path to financial independence. You reach it the moment your invested savings are large enough that, even if you never contribute another dollar, compound growth alone will carry them to your full retirement number by the time you retire. After that point you're "coasting": you still need to work to pay today's bills, but you no longer need to save for retirement at all.

The idea flips the usual FIRE math. Full FIRE asks how big a portfolio you need now to live off it immediately — typically 25 times your annual spending, based on the 4% rule. Coast FIRE instead discounts that future target back to today. If you need $1,000,000 at age 65 and your money grows at 5% a year after inflation, then at age 35 — 30 years out — you'd only need about $231,000 invested today, because three decades of compounding does the rest. That $231,000 is your Coast FIRE number. The further you are from retirement, the smaller it is, since growth has more time to work.

Why aim for it? Coast FIRE offers a powerful psychological and practical freedom long before full retirement. Once you hit it, you can throttle back: switch to a lower-paying but more enjoyable job, go part-time, start a business, or take a career break, knowing your retirement is already secured by the money you've banked. It's the foundation of Barista FIRE, where part-time work (sometimes for benefits) covers current costs while investments coast.

The key inputs are your years until retirement and your assumed real return — small changes in either move the number significantly, and a higher assumed return makes the target look easier but carries more risk. Because the calculation leans entirely on growth, it's sensitive to a poor run of early returns, so many people treat their Coast FIRE number as a floor and keep saving a little anyway. Use it as a motivating checkpoint: the day your balance crosses the line, your financial future largely takes care of itself.