Coast FIRE means you have already invested enough that, even if you never contribute another dollar, compound growth could carry the balance to your retirement target by your chosen age. Use this calculator to find your Coast FIRE number and see how long it takes to reach it.
Coast FIRE Calculator
Formula: Coast FIRE number = (yearly spending ÷ withdrawal rate) ÷ (1 + return)years to retirement. Returns are not guaranteed and this ignores inflation, taxes and Social Security, so treat the result as a planning estimate, not advice.
How to use this Coast FIRE calculator
- Enter your age, the age you want to retire and what you have invested today.
- Enter your monthly contribution and the yearly spending you expect in retirement.
- Choose a withdrawal rate (4% is a common starting point) and an expected return, then click calculate.
How the Coast FIRE number is calculated
First the tool sets your retirement target: yearly spending divided by the withdrawal rate (for example $50,000 ÷ 4% = $1,250,000). Then it discounts that target back to today using your expected return and the years remaining. With 35 years to go and a 7% return, the Coast FIRE number for a $1,250,000 target is about $117,000. We walk through the idea in Coast FIRE: What It Means and How to Calculate Your Number.
Frequently asked questions
What return should I use? Returns are not guaranteed. A lower, more conservative figure gives a larger Coast number and a safer plan; try several values to see the range.
Does this include inflation and taxes? No. Treat your spending figure as the amount you want in future dollars and test a few scenarios, or add a buffer.
Where should the money be invested? Many people use tax-advantaged accounts first; see the IRS 401(k) contribution limits and our Traditional vs. Roth IRA guide.
Sources: Investor.gov: Compound Interest Calculator
This calculator is for education and gives estimates only. It is not financial, tax or legal advice.