What is FIRE?
FIRE stands for Financial Independence, Retire Early. It's a movement built on a simple idea: if you save and invest a large share of your income, your portfolio can eventually generate enough passive income to cover your living expenses forever — freeing you from needing a paycheck decades before the traditional retirement age of 65.
Reaching FIRE comes down to two numbers: how much you need invested (your FIRE number), and how fast you can get there (driven mostly by your savings rate). This calculator computes both and projects the exact year your net worth crosses the finish line.
How this FIRE calculator works
The calculator runs a year-by-year compounding simulation using the numbers you enter. Each simulated year, your invested net worth grows by your expected return, then your annual savings (income minus expenses) are added on top:
The simulation repeats until your net worth reaches your FIRE target, then reports how many years that took and the age you'll be. The chart plots that trajectory against your target line so you can see the compounding curve steepen over time.
The inputs
- Current net worth — your total invested assets today.
- Post-tax income & expenses — the gap between these is your annual investable savings.
- Investment return rate — a long-run stock market average is often assumed near 7% after inflation.
- Safe withdrawal rate — the percentage you'll draw down each year in retirement, commonly 4%.
What is your FIRE number?
Your FIRE number is the size your portfolio must reach so that a safe withdrawal rate covers your yearly spending indefinitely. The formula is straightforward:
At the classic 4% withdrawal rate, that's the same as 25× your annual expenses. Spend $40,000 a year? Your FIRE number is $1,000,000. Spend $60,000? It's $1,500,000. This is why controlling expenses is so powerful — every dollar you cut from annual spending removes about $25 from the total you need to save.
The 4% rule and safe withdrawal rates
The 4% rule comes from the Trinity Study, which examined historical market data and found that retirees who withdrew 4% of their portfolio in year one — then adjusted that amount for inflation annually — had a very high probability of their money lasting 30 years or more.
It's a guideline, not a guarantee. More conservative early retirees planning for a 40–50 year horizon sometimes use 3.25%–3.5%, which raises the FIRE number but adds a margin of safety. You can test any withdrawal rate in the calculator above to see how it moves your target.
How to reach FIRE faster
The single most important lever is your savings rate — the percentage of your take-home pay you invest. It's more powerful than your income because it works on both sides of the equation at once: a higher savings rate grows your portfolio faster and shrinks the FIRE number you need.
Practical ways to raise your savings rate:
- Attack your three biggest costs first — housing, transportation, and food usually dwarf everything else.
- Direct every raise and windfall to investments before lifestyle inflation absorbs it.
- Maximize tax-advantaged accounts so more of each dollar stays invested and compounding.
- Grow income through skills or side work, then bank the difference rather than spending it.
The types of FIRE
FIRE isn't one-size-fits-all. Different flavors trade off how much you save versus how you live along the way:
Lean FIRE
Financial independence on a minimalist budget — often under $40k/year — with a smaller FIRE number and a frugal lifestyle.
Fat FIRE
Retiring with a generous budget and no lifestyle compromises, requiring a much larger portfolio to sustain higher spending.
Coast FIRE
You've invested enough early that compounding alone will carry you to full FIRE by traditional retirement age — you only need to cover current expenses.
Open the Coast FIRE calculator →Barista FIRE
A hybrid: part-time or lower-stress work covers some expenses while your portfolio handles the rest, bridging you to full independence.
Open the Barista FIRE calculator →Frequently asked questions
What is a FIRE number?
Your FIRE number is the amount of invested assets you need so that a safe withdrawal rate covers your annual expenses. At a 4% withdrawal rate this equals 25 times your yearly spending.
How is the FIRE number calculated?
FIRE number = annual expenses ÷ your safe withdrawal rate. For example, $40,000 of expenses at a 4% withdrawal rate gives a FIRE number of $1,000,000.
What is the 4% rule?
The 4% rule, based on the Trinity Study, suggests you can withdraw 4% of your portfolio in the first year of retirement and adjust for inflation each year, with a high probability the money lasts 30+ years.
What is the single biggest factor in reaching FIRE early?
Your savings rate. The percentage of income you invest matters far more than your absolute income, because a high savings rate both grows your portfolio faster and lowers the FIRE number you need to hit.
Is my data private?
Yes. This calculator runs entirely in your browser. Nothing you type is sent to a server or stored — refresh the page and it's gone.