What is Coast FIRE?
Coast FIRE is the point where the money you’ve already invested will grow into your retirement number with no new contributions. From then on, your paycheck only has to cover today’s bills. You still work, but you could take a lower-paid job, cut your hours or spend more, while compound growth finishes the job.
It’s a milestone, not retirement. The money stays invested until your retirement age, through bad years as well as good. Many people treat it as the halfway mark: save hard early, reach Coast FIRE in their 30s or 40s, then ease off.
How is the Coast FIRE number calculated?
Start with your FI number: the yearly spending your portfolio must cover, divided by your withdrawal rate. At 4%, $40,000 a year needs $1,000,000. Then discount that back to today at your expected return. At 5% a year over 35 years, $1,000,000 shrinks to $181,290. That’s your Coast FIRE number.
FI number = (retirement spending − other income) ÷ withdrawal rate
Coast FIRE number = FI number ÷ (1 + r)n
r is your real return and n the years until you retire. Everything is in today’s dollars, so the return must be after inflation. The number climbs every year you wait, because there’s less time left to grow. For a $1,000,000 FI number:
| Years to retirement | At 5% real | At 7% real |
|---|---|---|
| 40 | $142,046 | $66,780 |
| 30 | $231,377 | $131,367 |
| 20 | $376,889 | $258,419 |
| 10 | $613,913 | $508,349 |
“I’m 35 with $100,000 invested. Can I stop saving now and still retire at 65 on $40,000 a year?”
Not yet. You’d need $231,377 invested today at 5%, so you’re 43% of the way. Saving about $696 a month until 65 would get you there. Try this scenario
When can I stop saving?
When your portfolio catches up with your Coast FIRE number. Both are moving: your savings grow with every deposit, and the number you need rises each year as retirement gets closer. The calculator adds your savings month by month and finds the first month the two meet. From there, growth alone reaches your FI number on time.
“I’m 30 with $50,000 invested and save $1,000 a month. When can I stop?”
At about age 45 and 9 months, after putting in another $189,000. Left alone from then, the portfolio grows to $1,000,000 by 65. Try this scenario
“I’m 40 with $150,000 and can save $1,500 a month. I want $40,000 a year from 65.”
At about age 50 and 4 months. With 25 years to go, your Coast FIRE number today is $295,303. Try this scenario
If you never reach it, the results show the monthly saving that would hit your FI number by retirement instead. Stopping is also optional: the “If you never stop saving” figure shows the cushion you’d give up by coasting.
“I’m 25 with $10,000 and save $500 a month. Will I ever coast to $40,000 a year by 65?”
Not at $500. You’d reach about $812,000, so you’d need to save $627 a month for the full 40 years. Save more than that and you’d reach Coast FIRE early. Try this scenario
Is $500,000 enough for Coast FIRE?
It depends on how many years it has to grow and what you’ll spend. At 5% a year after inflation, $500,000 grows to about $814,000 in 10 years, $1.33 million in 20 and $2.16 million in 30. At a 4% withdrawal rate, that pays about $32,600, $53,100 or $86,400 a year.
“I’m 45 with $500,000 invested. Can I coast to $50,000 a year at 65?”
Yes. Your Coast FIRE number is $471,112, so you’re already past it, and the $500,000 grows to about $1.33 million by 65. Try this scenario
What return should I assume?
A real return, after inflation, because every amount here is in today’s dollars. For a mostly-stock portfolio, 4–5% is a common planning figure. U.S. stocks did better over most long stretches: since 1871, the median 35-year period returned 6.7% a year after inflation. The worst, 1886 to 1920, returned 3.3%.
The return matters more here than in most plans, because once you stop saving nothing new goes in to make up a shortfall. For the 30-year-old above, assuming 4% instead of 5% pushes the coast age from 45 to 58. Assuming 6% brings it down to 38.
“Same plan, but I want to be more cautious and assume 4%.”
You’d stop at age 58 instead of 45, after putting in $336,000 rather than $189,000. Try this scenario
The history check in the results compares your rate with every period of the same length in U.S. stock data since 1871. At 5% over 35 years, stocks matched or beat it in 85% of 121 periods. Coasting through the worst one would have taken $316,279 invested at the start instead of $181,290. That’s U.S. stocks only, with no fees or taxes, so treat it as a stress test, not a forecast.
Coast FIRE vs. Barista, Lean and regular FIRE
Regular FIRE means your portfolio already covers your spending, so work is optional. Lean and Fat FIRE are the same goal on a smaller or bigger budget. Coast FIRE comes earlier: your retirement savings are done, but you still work to pay the bills. Barista FIRE sits between them: you’ve saved enough that part-time work can cover the rest.
To plan for income that lasts through retirement, such as a pension or part-time work you’ll keep, enter it under More options as other income. It comes straight off the spending your portfolio must fund, so it shrinks both numbers. To find the date your portfolio covers everything, use the FIRE calculator.
“Same as the 30-year-old, but I expect $20,000 a year from a pension.”
The FI number halves to $500,000, and you could stop saving at about age 33 and 9 months. Try this scenario
Coast FIRE FAQ
Is Coast FIRE the same as retiring early?
No. At Coast FIRE your retirement savings are done, but you still need income for today’s spending until your planned retirement age. What changes is how much you must earn: enough to live on, not enough to live on and save. Many people use that room to cut hours or change careers.
What if the market falls after I stop saving?
A crash early on hurts, but what matters is the average return over the whole period, not one bad year. The real risk is a weak decade or two. If your portfolio falls well behind the Coast FIRE line on the chart, saving again for a few years puts you back on track.
Should I count Social Security?
You can, under More options as other income in retirement. It lowers the FI number, which lowers the Coast FIRE number. Use your estimate from ssa.gov in today’s dollars, and leave it out if you plan to retire well before you can claim, since the portfolio must cover those early years alone.
Do I have to stop saving once I reach Coast FIRE?
No. Coast FIRE tells you that you could stop, not that you should. Saving a little longer builds a cushion against weak returns or higher spending, or lets you retire earlier. The results show what you’d have if you never stopped, so you can see what coasting costs.
Formulas and the history check are documented on the methodology page. For how withdrawals held up once retired, see the 4% rule, tested on every 30-year retirement since 1871.
Sources
- Robert J. Shiller, U.S. stock market data (S&P Composite prices, dividends and CPI), Yale University. With S&P Dow Jones Indices for recent years, used for the history check.
- U.S. Bureau of Labor Statistics, Consumer Price Index for All Urban Consumers (CPI-U), used to turn returns into after-inflation returns.
- William P. Bengen, “Determining Withdrawal Rates Using Historical Data,” Journal of Financial Planning, October 1994. The origin of the 4% withdrawal rate.
- Social Security Administration, my Social Security, for your own benefit estimate.