What Coast FIRE means
Coast FIRE describes a halfway milestone on the road to financial independence. You have not yet saved enough to live off your portfolio, but you have saved enough that you never need to contribute again: left alone, your current investments will compound up to your full independence number by the time you retire. From that moment your only financial job is to cover today’s living expenses — the retirement problem is effectively solved in the background. This is quite different from fullFIRE, where the portfolio is large enough to support you immediately and work becomes optional altogether. Coast FIRE comes first and arrives years, sometimes decades, earlier.
Worked example
Take a 30-year-old with $100,000 invested who plans to retire at 60 on $50,000 a year, assuming a 7% real return and a 4% withdrawal rate:
| Step | Amount |
|---|---|
| Annual spending in retirement | $50,000 |
| ÷ 4% withdrawal rate = FIRE numberthe nest egg that sustains that spending indefinitely | $1,250,000 |
| Years left to compoundage 30 today, retiring at 60, at a 7% real return | 30 years |
| Current investmentson their own these grow to $761,226 by age 60 — $64,209 more is needed today to coast | $100,000 |
| = Coast FIRE numberinvested today and left untouched, this compounds to the full $1,250,000 by age 60 with no further contributions | $164,209 |
Computed with this calculator's default settings — open the tool above and you'll see the same numbers, then adjust the ages, balance, and return to match your own plan.
The maths: FIRE number first, then discount to today
The calculation runs in two steps. First you find your FIRE number — the nest egg that can sustain your retirement spending indefinitely — by dividing expected annual expenses by your safe withdrawal rate. At a four percent rate, fifty thousand of spending implies a target of one and a quarter million. Second, you discount that future target back to the present using your expected annual return over the years remaining until retirement. The present value you arrive at is the Coast FIRE number: the sum that, invested now and left untouched, grows into the full FIRE number on schedule. It is the same compounding mathematics behind ourcompound interest calculator, simply run in reverse to solve for the starting balance.
Why time and compounding do the work
The further you are from retirement, the smaller your Coast FIRE number, because money has more years to multiply. A modest balance in your twenties can quietly double several times over before you reach sixty, which is why coasting is most powerful for those who started early. The flip side is the caveat that keeps Coast FIRE honest: you still have to pay for your life in the meantime, so you need ongoing income for current expenses even after the retirement saving is done. And the real returns that make the projection work are assumptions, not promises — markets disappoint, inflation shifts, and a long coast leaves plenty of time for either. Treat the figure as a guide, revisit it as the years pass, and for a broader retirement picture see ourretirement calculator.
Frequently asked questions
What is Coast FIRE?
Coast FIRE is the point at which you have already invested enough that, with no further retirement contributions, ordinary market growth alone will carry your portfolio to your full financial-independence number by the time you retire. Once you reach it you can stop saving for retirement entirely and only need to earn enough to cover your current living expenses, letting compounding do the rest of the heavy lifting in the background.
How is Coast FIRE different from regular FIRE?
Regular FIRE means you have enough invested today to live off your portfolio right now, typically by withdrawing about four percent a year. Coast FIRE is a milestone reached much earlier: you do not yet have the full nest egg, but you have enough that you will get there through growth alone without adding another dollar. With full FIRE you can quit working; with Coast FIRE you still need a paycheque for living costs, but you are free from the pressure to keep saving.
How is the Coast FIRE number calculated?
First you find your FIRE number by dividing your expected annual retirement spending by your safe withdrawal rate, so spending of fifty thousand at a four percent rate gives a FIRE number of one and a quarter million. Then you discount that target back to today using your expected annual return over the years until retirement. The result is the Coast FIRE number — the amount that, invested now and left untouched, compounds up to your full FIRE number by retirement age.
What return should I assume?
Use a real return — that is, a growth rate already adjusted for inflation — because your future expenses will also rise with inflation. A common assumption for a diversified stock-heavy portfolio is around five to seven percent real, though the right figure depends on your asset mix and your own caution. A lower assumption raises your Coast FIRE number and gives you a margin of safety; a higher one lowers it but leaves less room for disappointing markets.
I have hit Coast FIRE — can I stop working?
No. Hitting Coast FIRE means you can stop saving for retirement, not that you can stop working altogether. Your invested money is on track to fund retirement on its own, but you still need income to pay for housing, food, and everything else between now and the day you retire. Coast FIRE buys you flexibility — a lower-stress job, fewer hours, or a career change — rather than the full freedom of regular FIRE.
Disclaimer: This calculator is foreducation and illustration only. Coast FIRE rests on simplifying assumptions — a single steady real return and a fixed withdrawal rate — and the figures it produces are projections, not guarantees. Real returns vary, inflation changes, and you still need income to cover current expenses. Nothing here is investment, tax, or retirement advice.