Coast FIRE Calculator
A Coast FIRE calculator tells you whether the retirement savings you already have will compound into a full retirement nest egg by your target retirement age with zero more contributions. Enter your age, current savings, expected return, and desired retirement spending in the calculator above.
For example, a 35-year-old with $150,000 saved, retiring at 65 with a 7% return and a $60,000-a-year spending goal, needs $197,051 invested today to coast — so that saver is not quite there yet and needs to keep contributing.
How it works
The calculator above works backward from your retirement goal. First, it turns your desired annual retirement spending into a target nest egg (your "FIRE number") using the safe-withdrawal-rate rule: spending divided by the withdrawal rate, so a $60,000 spending goal at a 4% withdrawal rate needs a $1,500,000 nest egg.
Next, it discounts that FIRE number back to today at your expected return, which gives your "coast number" — the amount you'd need invested right now, untouched, to grow into your FIRE number by retirement through compounding alone. If your current savings already clear that number, you've reached Coast FIRE: you could stop contributing entirely and still retire on schedule. If not, the calculator simulates your real monthly contribution month by month to find the exact age you'd cross the coast number, since that number shrinks every month your investments grow.
The Coast FIRE idea matters because it separates two different jobs: saving enough principal, and then giving that principal time to compound. Once you've coasted, extra income can go toward paying down debt, working fewer hours, or a lower-stress career change, because your retirement is already funded by growth. Use our retirement calculator to model your full retirement plan with continued contributions, or the investment calculator to project a taxable brokerage account using the same compounding math.
Frequently asked questions
What is Coast FIRE?
Coast FIRE is the point where your current retirement savings, left to grow untouched at your expected return, will compound into your full retirement number by your target retirement age without any more contributions. Once you reach it, you can "coast" — keep working or not, but stop adding to retirement and still retire on time.
How is the Coast FIRE number calculated?
First, your desired annual retirement spending is divided by a safe withdrawal rate (commonly 4%) to get your FIRE number — the full nest egg you need. That FIRE number is then discounted back to today at your expected annual return over your years until retirement, which gives the amount you'd need invested right now to coast.
What is a good expected return to use?
A common planning assumption for a diversified stock-heavy portfolio is 6% to 8% annually after inflation. Using a lower return is more conservative and raises your coast number; a higher return lowers it but assumes more risk. Try a few different rates in the calculator to see how sensitive your result is.
Is Coast FIRE the same as full FIRE?
No. Full FIRE (Financial Independence, Retire Early) means you already have enough invested to retire and live off withdrawals now. Coast FIRE means your current savings will grow into that number LATER, by your target retirement age, without more contributions — you're not retiring yet, just no longer required to save for retirement.
What if I haven't reached Coast FIRE yet?
The calculator shows both your gap today and, if you enter a monthly contribution, the specific age you're projected to reach Coast FIRE by continuing at that pace. Contributing more, extending your timeline, or accepting a higher (riskier) expected return all move that date earlier.
Sources
We prioritize primary sources for rules, formulas, rates, limits, and definitions. See our calculator methodology and editorial policy.