QuietCalcsWhat is Coast FIRE?
In the FIRE (Financial Independence, Retire Early) world, your FIRE number is the portfolio that can fund your retirement spending indefinitely — conventionally 25× annual spending, from the 4% safe withdrawal rate. Coast FIRE asks a gentler question: how much do I need invested today so that growth alone gets me there by retirement age?
Once you cross that threshold, retirement saving is optional. You still need to earn enough to cover your living costs — but every dollar you earn beyond that is yours to spend, and your retirement quietly builds itself in the background.
The Coast FIRE formula
FIRE number = annual spending ÷ safe withdrawal rate
Coast FIRE number = FIRE number ÷ (1 + r)years until retirement
Worked example: you're 30, plan to retire at 65, and want $40,000/year in today's dollars. At a 4% withdrawal rate your FIRE number is $1,000,000. With a 5% real return over 35 years, your Coast FIRE number is 1,000,000 ÷ 1.0535 ≈ $181,000. Reach $181k at age 30 and compounding does the remaining work by itself.
If you haven't reached it yet, the calculator projects your balance month by month with your current contributions and finds the age where you cross the (rising) threshold — that's your coast date.
Why "after inflation" returns matter
The calculator works in real (inflation-adjusted) terms, which keeps everything in today's dollars: your $40,000 of spending stays meaningful, and the FIRE number you're aiming at doesn't silently inflate. Historically, broad U.S. stock indexes have returned roughly 7% per year after inflation over long periods; a 5% default is a deliberately moderate assumption, and you can set anything you like. Using nominal returns here (say 10%) would overstate your progress — don't.
Coast FIRE vs. its cousins
- Coast FIRE — enough invested that growth alone reaches your number; you still work to pay the bills.
- Barista FIRE — a step further: part-time work covers part of your spending while withdrawals cover the rest, often bridging to benefits eligibility.
- Lean / Fat FIRE — the same math with a frugal (≈$25k–40k) or generous (≈$100k+) spending target.
What this calculator doesn't know
Real life is lumpier than a smooth growth curve. Sequence-of-returns risk (a crash early in retirement hurts more than the average suggests), taxes on withdrawals, healthcare before Medicare or your country's equivalent, and pensions or Social Security are all outside this model. Treat the result as a well-grounded estimate for planning, not a guarantee — and stress-test it by trying a 3.5% withdrawal rate and a 4% return.
Frequently asked questions
What return should I assume?
A common range is 4–7% after inflation for a stock-heavy portfolio over multiple decades. The default here is 5%, which builds in a margin of safety versus the long-run historical average of roughly 7% real for U.S. stocks.
Is the 4% rule safe?
The 4% rule comes from the Trinity Study, based on 30-year U.S. retirements. For longer horizons — common with early retirement — many people plan on 3.25–3.75% instead. Try both in the calculator; the difference in your Coast number is substantial.
What if I keep contributing after reaching Coast FIRE?
Then you'll pass your FIRE number early or retire on more than planned. Coast FIRE marks the point where contributions become optional, not forbidden — the chart shows contributions stopping only to demonstrate that growth alone suffices.
Does this include Social Security or a pension?
No. Any guaranteed income reduces the spending your portfolio must cover — subtract it from the annual spending input for a rough adjustment.
Can my Coast FIRE money live in a 401(k) or IRA?
Yes — retirement accounts are actually a natural fit, since Coast FIRE money is meant to be left alone until traditional retirement age anyway. Early-access rules only matter if you plan to retire well before then.
Is my data stored?
Only in your own browser (so your numbers are still there tomorrow). Nothing is uploaded — the entire calculation runs locally.
Can I use this in pounds, euros, or another currency?
Yes — pick your currency and everything reformats, including the chart. Coast FIRE math is currency-neutral: the formula only cares that your spending, portfolio, and returns are in the same units. FIRE communities in the UK and Europe use exactly the same arithmetic.
Related calculators
Overtime Pay Calculator — overtime is one of the fastest ways to accelerate your coast date.
Time Card Calculator — track the hours behind the money.