FIRE Calculator
Work out your FIRE number — the portfolio that covers your spending forever — and how many years of saving and compounding it will take you to reach it.
Reviewed by the CalcCafe editorial team · Last updated 18 July 2026 · How we test our tools
Example
You are 30 with $100,000 invested, you save $30,000 a year, expect a 7% real return, plan on $40,000 of annual retirement spending, and use a 4% safe withdrawal rate. Your FIRE number is 40,000 ÷ 0.04 = $1,000,000. Each year the portfolio grows 7% and then the $30,000 of savings is added: it crosses $1 million after 15 years (ending near $1,029,774), making your FIRE age 45.
How it works
FIRE number = annual expenses ÷ (safe withdrawal rate ÷ 100) — at the classic 4% rate that is 25× your yearly spending. The tool then simulates your portfolio one year at a time: balance = balance × (1 + real return) + annual savings, repeating until the balance reaches the FIRE number (capped at 100 years). Years to FIRE is the number of iterations, and FIRE age is your current age plus that count. Because the return input is a real (after-inflation) return, all figures are in today's dollars.
Good to know
The 4% rule comes from the Trinity study, which back-tested US stock-and-bond portfolios and found that an initial 4% withdrawal, adjusted for inflation each year, survived nearly every historical 30-year retirement. Its caveats matter for early retirees: the study assumed a 30-year horizon, US market history, and negligible fees. A retirement that must last 50 years argues for a more conservative 3–3.5% rate — which raises the target from 25× spending to roughly 29–33×. Enter your own rate above to see how much the goal moves.
FIRE comes in flavors. Lean FIRE means retiring on a frugal budget (often under ~$40,000 a year), which shrinks the target but leaves little slack. Fat FIRE funds a comfortable lifestyle and typically needs $2.5 million or more. Coast FIRE means you have saved enough young that compounding alone will fund a normal-age retirement, so you only need to cover current expenses. Barista FIRE blends a smaller portfolio with part-time work that covers some spending — and, in the US, often health insurance.
This calculator uses a real (inflation-adjusted) return, which is why the answer is in today's dollars. Historically, US stocks have returned roughly 10% nominal but closer to 7% after inflation, which is why 7% is the default here. If you enter a nominal return instead, the tool will flatter you: it would treat inflation-era dollars as if they bought today's lifestyle. Keep expenses, savings and return all in real terms and the projection stays internally consistent.
Your savings rate is the dominant lever — more powerful than squeezing an extra point of return. Saving more works twice: it grows the portfolio faster and it proves you live on less, which cuts the FIRE number itself. Remember, too, that the simulation assumes the average return arrives every year. Real sequences do not, and a deep bear market in the first years of retirement — sequence-of-returns risk — can sink a plan that looks fine on average. Flexible spending, a cash buffer or part-time income in early retirement are the usual defenses.
Frequently asked questions
What is a FIRE number and how is it calculated?
Your FIRE number is the portfolio size that can fund your annual spending indefinitely. It equals annual expenses divided by your safe withdrawal rate — at the classic 4% rate that is 25 times yearly spending, so $40,000 of expenses needs $1,000,000 invested.
Should I use a real or nominal return in this calculator?
Use a real, after-inflation return — around 7% is the long-run historical figure for US stocks. Because the return is real, the FIRE number, savings and expenses all stay in today's dollars, and the years-to-FIRE answer remains meaningful.
Is my financial data uploaded anywhere?
No — this calculator runs entirely in your browser. Your age, portfolio and savings figures never leave your device, and the tool works offline once the page has loaded.
Is this FIRE calculator free?
Yes, completely free with no sign-up and no limits. Rerun it with different savings rates, withdrawal rates or return assumptions as often as you like.
People also ask
Is the 4% rule safe for early retirement?
It was validated for 30-year retirements using US historical data. For a 40–50 year early retirement many planners prefer 3–3.5%, which raises the target to roughly 29–33 times annual spending. Flexibility to cut spending in bad markets also greatly improves survival odds.
How much do I need to retire at 45?
Divide your expected annual spending by your withdrawal rate: $40,000 a year at 4% needs $1 million; $80,000 needs $2 million. Then check whether your current portfolio plus yearly savings, compounding at a real return, can reach that figure by 45.
What is the fastest way to reach FIRE?
Raise your savings rate. It accelerates the portfolio and simultaneously lowers the spending your portfolio must support, so the FIRE number itself falls. Going from saving 15% to 40% of income typically cuts decades off the timeline — far more than chasing higher returns.
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Sources & references
These tools follow our methodology and provide educational estimates only — verify important figures with a qualified professional.