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FIRE Calculator (Financial Independence, Retire Early)

Find your FIRE number — the portfolio size you need to cover your expenses forever — and see how many years of saving it will take to get there.

Your FIRE number $1,000,000
Years to reach FI 20
Projected FI age 50

How the FIRE calculator works

FIRE stands for Financial Independence, Retire Early — the idea of building a large enough investment portfolio that withdrawals from it can cover your living expenses indefinitely, without depending on continued employment income. This calculator answers two questions: how big does that portfolio need to be, and how many years of saving will it take to get there?

Your FIRE number is calculated with a simple formula: FIRE Number = Annual Expenses / (Safe Withdrawal Rate / 100). At the commonly used 4% withdrawal rate, this is the same as the "25x rule" — 25 times your annual expenses — because 1 divided by 4% is 25. Lowering the withdrawal rate to be more conservative (say, 3.5%) raises the FIRE number, since a smaller rate needs a bigger portfolio to produce the same income.

Years to reach FI is calculated by simulating your portfolio's growth one year at a time: each year, your balance grows by your expected return and then your annual contribution is added, and the calculator counts how many years it takes until your balance reaches your FIRE number. If your current age is provided, the calculator adds the years-to-FI figure to it to show a projected FI age.

Worked example

Suppose you have $50,000 currently invested, add $20,000 a year, expect a 7% average annual return, plan to spend $40,000 a year in retirement, and want to use the standard 4% safe withdrawal rate.

FIRE Number = $40,000 / 0.04 = $1,000,000

Simulating the portfolio growing at 7% a year with a $20,000 annual contribution, the balance crosses $1,000,000 after 20 years. Starting at age 30, that puts your projected FI age at 50.

Choosing a safe withdrawal rate

The withdrawal rate you choose has a bigger effect on your FIRE number than almost any other input, because it's the denominator in the formula. The widely cited "4% rule" comes from historical U.S. market research (the Trinity Study) testing how often a 4% initial withdrawal, increased annually for inflation, would have lasted at least 30 years without running out of money. Retiring earlier than a traditional 30-year retirement — which is the whole point of FIRE — means your money needs to last longer, which is why many people in the FIRE community use a more conservative rate, such as 3% or 3.5%, instead of 4%.

A lower withdrawal rate produces a larger, more conservative FIRE number and therefore takes longer to reach — try lowering the rate in this calculator to see how much bigger a "safety margin" costs you in extra years of saving.

Common mistakes to avoid

1. Using a nominal return without adjusting for inflation

If you enter a return like 9-10% (a typical long-run nominal stock market average) but plan to spend your FIRE number in today's dollars, you'll overstate how quickly you'll get there, because inflation will have eroded some of that growth. Using a "real" (after-inflation) return — commonly estimated around 5-7% for a diversified stock portfolio — keeps the FIRE number and years-to-FI figure in consistent, comparable dollars.

2. Treating the FIRE number as the finish line, not a floor

This calculator's FIRE number assumes your expenses, withdrawal rate, and returns stay exactly as entered forever — it doesn't build in a buffer for market downturns early in retirement, healthcare costs, or lifestyle changes. Many people treat their calculated FIRE number as a minimum, not a target to stop exactly at.

3. Forgetting that contributions and returns compound together

Because the simulation adds your contribution every year on top of compounding growth, small increases in your annual contribution can meaningfully cut years off your timeline, especially in the earlier years before compounding has done most of the work. Try raising the annual contribution in this calculator to see how sensitive your years-to-FI figure is to how much you save.

Frequently asked questions

What is a good safe withdrawal rate for FIRE?

The "4% rule" comes from the Trinity Study, which found a 4% initial withdrawal rate (adjusted annually for inflation) survived a 30-year retirement in most historical market scenarios. Some planners use a more conservative 3-3.5% for extra safety or longer retirements, while others use 5% for shorter horizons. This calculator lets you set your own rate.

What is a FIRE number?

Your FIRE number is the total portfolio size needed so that your chosen withdrawal rate covers your annual expenses indefinitely. It's calculated as annual expenses divided by your withdrawal rate — at the classic 4% rate, that's the same as 25 times your annual expenses.

Does this calculator account for inflation?

Not directly — the expected return you enter should already reflect what you expect after inflation (a "real" return) if you want the FIRE number and years-to-FI figures to be in today's dollars. Long-term stock market projections often use a real return of roughly 5-7%, versus 9-10% nominal (before inflation).

Does the years-to-FI figure account for taxes?

No — contributions and growth are treated as fully available, with no tax drag modeled. Retirement accounts, taxable brokerage accounts, and different withdrawal strategies all have different tax treatments, so treat the years-to-FI figure as an optimistic estimate rather than an exact plan.

What if my current savings already exceed my FIRE number?

Then this calculator shows 0 years to FI — you've already reached your target by this calculation. That said, this only reflects the inputs you entered, not every real-world factor (fees, health insurance, ongoing income), which is why many people keep building a buffer beyond their initial FIRE number.