Coast FIRE Calculator
Calculate your Coast FIRE number — the amount needed today so compound growth alone funds retirement.
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Coast FIRE is the point where your invested assets, left untouched, will grow to fund your full retirement on their own. Once you hit that number, you can stop saving for retirement entirely — you only need to cover current living expenses. This calculator tells you your Coast FIRE number, how far you are from it, and whether you're already there without knowing it.
Example
Retirement age: 65
Formula
Coast FIRE number = Retirement goal ÷ (1 + real return rate)^years to retirement Retirement goal = Annual expenses in retirement × 25 (the 4% rule) Years to retirement = Target retirement age − Current age
How Compound Growth Does the Work
Money doubles roughly every 10 years at 7% real return (rule of 72). A $262,000 portfolio at 35 becomes ~$524k at 45, ~$1M at 55, and ~$2M at 65 without another dollar added. The earlier you reach your Coast number, the more dramatically compounding works in your favour. This is why front-loading retirement savings in your 20s and 30s is so powerful.
Frequently Asked Questions
What return rate should I use?
7% real (inflation-adjusted) is a common conservative assumption for a diversified stock/bond portfolio over 30+ years.
What is the 4% rule?
A rule of thumb that says you can withdraw 4% of your portfolio annually in retirement with a high probability of the money lasting 30 years.
Do I need to stop working after reaching Coast FIRE?
No — you just don't need to save for retirement anymore. Many people continue working part-time or in passion projects to cover current expenses.
Does this include Social Security?
No. Social Security reduces how large a nest egg you need. Subtract your expected SS benefit × 25 from your retirement goal before calculating.