Coast FIRE Calculator
Find the amount you need invested today so you can stop saving for retirement and let compounding do the rest. Results update as you type.
Your Coast FIRE number by age
The earlier you hit your number, the less you need, compounding has more time to work. Based on your inputs above:
| If you're this age… | You need invested today | Years to grow |
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What is Coast FIRE?
Coast FIRE is the moment your invested savings become large enough that, without you adding another penny, compound growth alone will carry them to your full retirement number by the age you plan to retire. You still work, and you still pay this month's bills from this month's salary. What stops is retirement saving. Your future is already funded; you are simply coasting toward it.
It is the most useful milestone in personal finance that almost nobody is taught, because it arrives decades before full financial independence and it changes your options immediately rather than eventually.
The two numbers that drive everything
Every calculation on this site rests on two figures, and it is worth being precise about the difference:
- Your FIRE number is the portfolio that funds your lifestyle indefinitely. Using the 4% rule from the Trinity Study, it is your annual spending divided by 4%, which is the same as spending × 25. Someone spending $40,000 a year needs $1,000,000.
- Your Coast FIRE number is that same target discounted back to today at your expected real return. It answers a different question: not "how much do I need in the end?" but "how much do I need right now so the end takes care of itself?"
FIRE number = annual spending ÷ withdrawal rate
Coast FIRE number = FIRE number ÷ (1 + real return)years to retirement
real return = nominal return − inflation − fees
Everything is expressed in today's money, which matters more than it sounds. Inflation is subtracted from your return rather than added to your target, so when the calculator says $253,415 it means $253,415 of today's purchasing power, directly comparable to today's salary and today's grocery bill.
A worked example, start to finish
Take a 30-year-old planning to stop work at 65, expecting to spend $40,000 a year in retirement, using a 7% nominal return, 3% inflation and the standard 4% withdrawal rate.
Step 1 — the FIRE number
$40,000 ÷ 0.04 = $1,000,000
The portfolio that funds a $40,000 lifestyle indefinitely.
Step 2 — the real return
7% − 3% inflation = 4% real
Growth after inflation, which is the only growth that buys anything.
Step 3 — discount it back 35 years
$1,000,000 ÷ (1.04)35 = $253,415
That is the Coast FIRE number. Invest $253,415 by age 30, never contribute again, and compounding delivers roughly $1,000,000 by 65, in today's money.
The leverage here is the exponent, not the rate. Those 35 years multiply the money almost fourfold. It is also why the same target at 45 requires $456,000 rather than $253,000: fewer years, less compounding, more cash needed up front.
How people actually reach it
The arithmetic is easy. Reaching the number is the work. Four levers do nearly all of it:
- Front-load your twenties and thirties. A dollar invested at 25 does roughly double the work of a dollar invested at 45. This is the single largest advantage available to anyone young, and it expires quietly.
- Raise the gap, not just the income. Your savings rate, the share of take-home pay you keep, sets the timeline more than your salary does. The savings rate calculator shows the relationship in years.
- Control fees. You cannot choose your returns; you can choose your costs. A 1% annual fee compounds into years of extra work over a career. See index funds for FIRE.
- Be honest about retirement spending. Every $1,000 of annual spending you can genuinely live without removes $25,000 from the target at a 4% withdrawal rate.
Coast FIRE compared with the other finish lines
Coast FIRE is one of several targets, and they demand very different portfolios. For the same $40,000-a-year spender:
The full comparison covers when each one makes sense, and the complete Coast FIRE guide goes deeper on the mechanics. If you want the number for your own country or state, we computed it for all 50 US states and 162 countries using official price data.
What changes when you get there
Reaching Coast FIRE rarely means quitting the next morning. What it changes is leverage. Retirement is no longer a bill you owe every month, so the calculation behind every career decision shifts: a lower-paid job you enjoy becomes affordable, four-day weeks become arithmetic rather than fantasy, and a bad manager becomes a choice rather than a life sentence. Many people change nothing at all except how it feels to go to work, and keep investing anyway, which pulls full independence closer still.
The honest caveat: Coast FIRE assumes you keep earning enough to cover current costs, and it assumes markets roughly cooperate. Re-run your numbers once a year. A long flat market, a move, or a change in planned spending can quietly undo coast status, and catching that early costs almost nothing while catching it late costs years.
How this calculator works
Your current investments and any monthly contributions are compounded forward month by month at your real return. The chart marks where that curve crosses your FIRE target, and the table above it recomputes the coast number for every age using your own assumptions rather than ours. Nothing is sent anywhere: the maths runs entirely in your browser, so your figures never leave your device.
Frequently asked questions
How do I know if I've reached Coast FIRE?
Enter your current investments and set your monthly contribution to 0. If your projected net worth at retirement still reaches your FIRE target, you've hit Coast FIRE, the status box turns green.
What return rate should I use?
A common conservative assumption is 7% nominal (roughly 4–5% after 2–3% inflation). The US market has historically returned ~10% before inflation, but planning with a lower number builds a safety margin. Adjust it under "Advanced assumptions."
Does this account for inflation?
Yes, we subtract your inflation rate from your investment return, so every figure is in today's dollars. You don't need to guess future cost-of-living increases.
Can I still contribute after reaching Coast FIRE?
Absolutely, you'll reach full FIRE earlier and retire with a larger cushion. Coast FIRE just means you no longer have to save.
Is the 4% rule safe?
The 4% safe withdrawal rate comes from the Trinity Study and held up over 30-year historical periods. Some people use 3.5% for extra caution, adjust it in the advanced settings.