What is a FIRE calculator?
A FIRE calculator estimates how long it will take to become financially independent — the point where your invested savings are large enough that their returns can cover your living expenses, so working becomes optional. It centers on two numbers: your FIRE number (the portfolio you're aiming for) and the years to reach it given how much you save and earn on your investments. The math reveals a surprising truth — your income matters less than the percentage of it you keep.
How to use this calculator
- Enter your age and current investments — the money already working for you in retirement and brokerage accounts.
- Enter your annual take-home income and expenses. The gap between them is what you invest each year.
- Set a real return and withdrawal rate (5% and 4% are common defaults) and press Calculate to see your FIRE number, years to FI, and the age you'll get there.
Example
A 30-year-old has $50,000 invested, earns $90,000 take-home, and spends $50,000 a year — a 44% savings rate. With a 4% withdrawal rate, their FIRE number is $50,000 × 25 = $1.25 million. Investing the $40,000 annual surplus at a 5% real return, they reach financial independence in roughly 18 years, at about age 48. Cut expenses to $40,000 and the timeline shrinks on both ends — they need less and save more.
Frequently asked questions
What is FIRE?
FIRE stands for Financial Independence, Retire Early. You save and invest a large share of your income until your portfolio's returns can cover your living expenses indefinitely, freeing you from needing a paycheck.
What is my FIRE number?
It's the portfolio size that can sustainably fund your lifestyle — your annual expenses divided by your safe withdrawal rate. At a 4% withdrawal rate that's 25× your annual expenses.
What is the 4% rule?
From the Trinity Study: you can withdraw about 4% of your portfolio in year one of retirement, adjusting for inflation after, with a high chance the money lasts 30+ years. Conservative early retirees use 3–3.5%.
Why does my savings rate matter so much?
It's the biggest lever in early retirement. A higher savings rate grows your portfolio faster and lowers the FIRE number you need, because you live on less. Going from 20% to 50% can cut decades off the timeline.
Should I use a real or nominal return?
Use a real return — your expected return after inflation, around 5–7% for a stock-heavy portfolio historically. That keeps your FIRE number and result in today's dollars.