Coast FIRE Calculator

Find your Coast FIRE number and the exact age you can stop saving — the moment your invested money will compound to your retirement target on its own. Instant, no sign-up, formula shown.

yr
yr
$
$
$
In today's dollars — what your lifestyle costs per year.
%
The classic rule is 4%. Lower = more conservative.
%
%
We work in real dollars: return minus inflation.
You can stop saving at
—
—
    FIRE number$0
    Coast number today$0
    If you stop today$0

    The moment you hit Coast FIRE

    Green is your portfolio; indigo is the Coast FIRE target (it rises toward your FIRE number as retirement nears). Where green crosses indigo, you can stop saving.

    How your monthly contribution changes the date

    Saving more each month brings your Coast FIRE age forward — see exactly how much.

    Monthly contributionCoast FIRE ageFrom now

    The exact formula — with your numbers

    Your FIRE number, then discounted to today at your real (inflation-adjusted) return:

    Coast = Spending / SWR(1 + r)t

    Spending = annual retirement cost · SWR = safe withdrawal rate · r = real return (nominal − inflation) · t = years to retirement. We then simulate your contributions month by month to find when your portfolio first crosses this target.

    How to use this Coast FIRE calculator

    1. Enter your age and target retirement age. The gap is how long your money has to compound.
    2. Add what you have invested and save monthly. Only long-term retirement/brokerage money counts — not your emergency fund.
    3. Set your retirement spending and withdrawal rate. Spending ÷ SWR is your FIRE number in today's dollars.

    What Coast FIRE actually means

    Reaching Coast FIRE doesn't mean you can quit working — it means you can stop saving for retirement. Your invested money is now big enough that compounding alone will carry it to your FIRE number by your target age. From that point you only need to earn enough to cover today's bills, which opens the door to lower-stress jobs, part-time work, or a career pivot. Every dollar you keep investing past Coast FIRE simply lets you retire earlier or with more.

    Frequently asked questions

    What is Coast FIRE?

    It's the point where your existing investments will grow into your full FIRE number by retirement with no further contributions. You still cover current expenses, but you're done saving for retirement.

    Why use a real return instead of a nominal one?

    Because your FIRE number is in today's dollars. Using a real return (nominal minus inflation) keeps everything in today's purchasing power, so the answer means what you think it means.

    What if the calculator says "not on track"?

    At your current monthly amount your portfolio never catches the Coast FIRE line before retirement. Raise the monthly contribution, push retirement out a few years, or lower planned spending — the comparison table shows how each change moves the date.

    Method & sources

    • Calculation: FIRE number = annual spending ÷ safe withdrawal rate; Coast number = FIRE ÷ (1 + real return)years; contributions simulated monthly in real dollars. Verified against an independent test suite.
    • The 4% safe withdrawal rate comes from the widely cited Trinity study; it is a planning guide, not a guarantee.
    • Reviewed: · Assumptions reviewed quarterly.

    Educational estimate, not financial advice. Investment returns vary and can be negative.