Should I use a real or nominal return in a FIRE calculator?

Use a real (after-inflation) return, such as the 7% default, and enter expenses in today's dollars. That way the FIRE number and the timeline both come out in today's purchasing power, without needing a separate inflation input.

Does this FIRE calculator account for taxes?

Not separately. Treat your monthly retirement expenses as gross spending — everything you will pay out, including income tax on withdrawals and health insurance. If you expect to owe tax on withdrawals, pad the expense number rather than the return.

FIRE Calculator — When Can You Retire Early?

Q: Is the 4% rule safe for early retirees?

The 4% rule comes from the Trinity study, which tested 30-year retirements. If you retire at 35 your money may need to last 50+ years, so many early retirees plan around 3.25–3.75% instead. Lower the safe withdrawal rate in the calculator and your FIRE number rises accordingly.

FIRE Awareness · free calculator · runs in your browser

Current invested net worth ($)

Monthly savings ($)

Monthly expenses in retirement ($)

Expected return (%/yr, after inflation)

Safe withdrawal rate (%)

Your FIRE number

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until financial independence

This is the rough math. FIRE Awareness tracks the real thing — your live safe-to-spend number, worked back from your actual FIRE date.

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What this calculator actually computes

Two numbers matter in FIRE math. The first is your FIRE number — the portfolio size at which withdrawals can cover your spending indefinitely. The second is the date — how long compounding plus your monthly contributions take to get there. Everything else is decoration.

Your FIRE number is just your annual spending divided by your safe withdrawal rate:

FIRE number = annual expenses ÷ SWR

At the classic 4% rate that works out to 25× your annual expenses. Spend $40,000 a year and you need $1,000,000. Drop the SWR to 3.5% and the multiple becomes ~28.6×, so the same spending needs about $1,143,000. Small changes to the withdrawal rate move the goal a lot — which is exactly why it's an input here, not a hidden assumption.

For the timeline, the calculator doesn't use a closed-form shortcut. It simulates month by month: your balance grows by one month of return, your savings land on top, repeat until the balance crosses the goal. If that takes more than 100 years, it tells you honestly that you're not on this path yet — the fix is more savings, lower planned spending, or both.

A worked example

Say you have $100,000 invested, save $3,000 a month, and plan to spend $40,000 a year ($3,333/mo) in retirement. At a 4% SWR your FIRE number is $1,000,000. Growing at 7% a year with $3,000/mo added, you cross it in roughly 13 years. Notice what dominates: at this savings rate, contributions do most of the early lifting, then compounding takes over in the back half. That's typical — the first $100k is the slowest.

Honest caveats

Inflation. The 7% default is meant as a real (after-inflation) return — roughly what a global stock portfolio has averaged over long periods. Keep expenses in today's dollars and the answer comes out in today's dollars. If you enter a nominal return like 10%, your date will look flattering and wrong.
The 4% rule is a 30-year rule. It comes from the Trinity study of 30-year retirements. Retire at 35 and you may need 50+ years, so many early retirees plan on 3.25–3.75% instead.
Sequence-of-returns risk. A steady 7% never happens. A bad decade right after you retire hurts far more than the same decade later. Real plans need flexibility — spending cuts in bad years, or some part-time income.
Taxes and healthcare. Neither is modeled. Bake them into your monthly expense number.
This is a planning estimate, not financial advice.

FAQ

Is the 4% rule safe for early retirees? It's a reasonable starting point, not a guarantee. For horizons beyond 30 years, most careful FIRE plans use 3.25–3.75% — lower the SWR input and watch your number rise.

Real or nominal returns? Real. Use an after-inflation return and today's-dollar expenses, and you never need an inflation input at all.

What about taxes? Treat your retirement expense figure as gross — everything you'll pay out, including tax on withdrawals and health insurance.

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