What is Coast FIRE?
Coast FIRE is the point where you've saved enough that — even if you stop contributing entirely — your money will compound on its own and hit your retirement goal by the time you want to retire. You've "front-loaded" the hard work. After that, you can coast.
It's one of the most liberating milestones in personal finance because it uncouples your job from your retirement. You still need income to live on, but you're no longer racing to save for the future — the math is already done.
The Coast FIRE formula
Your Coast FIRE number is simply your retirement goal discounted back to today's dollars using your expected return rate:
Where r is your expected annual return (as a decimal) and years_to_retirement is the number of years between now and when you want to stop working. If your current savings already equal or exceed this number, you've hit Coast FIRE.
What return rate should I use?
The historical U.S. stock market average (S&P 500) is roughly 10% nominal or 7% after inflation. For retirement planning, most people use 6–8% to be a little conservative. If your money is sitting in a savings account, use whatever rate that pays. The lower the rate, the higher your Coast FIRE number — so being conservative here is wise.
Coast FIRE vs. lean FIRE vs. regular FIRE
- Coast FIRE — you've saved enough to stop contributing; you still work to cover living expenses.
- Lean FIRE — fully retired on a tight budget (usually ~25× very lean annual spending).
- FIRE — fully retired on your normal spending (25× rule).
- Fat FIRE — retired with extra breathing room (often 30–35× spending).
Coast FIRE is often the first FIRE milestone people can realistically hit. It's also underrated — once you're coasting, the pressure of every career decision changes completely.
This tool assumes a constant annual return rate and does not account for taxes, fees, inflation, or Social Security. It is for educational illustration only and is not financial advice. Real investment returns vary.