Coast FIRE Calculator
Calculate your Coast FIRE number and whether your current savings can grow to fund retirement without any additional contributions.
Coast FIRE is one of the most useful intermediate milestones on the path to full financial independence. It answers a specific question: have I saved enough that, even if I stop contributing entirely today, my investments will grow to full retirement funding by retirement age? Reaching Coast FIRE means you no longer need to save for retirement, only for current living expenses. That unlocks significant career and lifestyle flexibility.
Coast FIRE number = FI Number / (1 + return rate)^years to retirement. If you need $1,500,000 at 65 and have 27 years at 7% return, your Coast FIRE number is $1,500,000 / (1.07^27) = $1,500,000 / 6.21 = approximately $242,000.
What Coast FIRE enables
Once you have hit Coast FIRE, you have options that most people do not. You can take a lower-paying job you enjoy more, reduce hours, start a business with lower income, take a sabbatical, or move somewhere with lower cost of living, all without jeopardizing retirement. You still need to cover current living expenses, but the retirement savings pressure is gone. This is why Coast FIRE is often described as buying back work flexibility.
The math behind coasting
The Coast FIRE number is just the present value of your FI number. Your FI number is the portfolio needed at retirement to fund your desired income at the safe withdrawal rate: FI number = annual income / SWR. At 4% SWR and $60,000/year desired income, the FI number is $1,500,000. The Coast FIRE number is this discounted back to today at your expected investment return. The more years until retirement, the lower the Coast FIRE number.
Frequently asked questions
What is the difference between Coast FIRE and Lean FIRE or Fat FIRE?
Lean FIRE and Fat FIRE refer to the level of spending in retirement. Lean FIRE is full retirement on a reduced income. Fat FIRE is full retirement on a generous income. Coast FIRE is not a retirement status; it is a savings milestone that says you can stop actively saving for retirement. You still work, just without retirement savings pressure.
Does Coast FIRE account for inflation?
Using a real return rate (after inflation, typically 5-7% for diversified portfolios) makes the calculation inflation-adjusted. If you enter 7% as your return and inflation is 3%, use 4% real return for a more conservative inflation-adjusted estimate. The desired retirement income should be in today's dollars if you use real returns.