What Is FIRE?

FIRE stands for Financial Independence, Retire Early. At its core it's a simple idea: save and invest aggressively enough that your portfolio generates enough income to cover your living expenses — permanently. At that point, paid work becomes optional.

The movement gained mainstream attention in the 2010s, but the underlying math has been around for decades.

The Two Parts of FIRE

It helps to separate the two halves:

Financial Independence (FI) is the milestone. You've accumulated enough invested assets that you no longer need a paycheck to sustain your lifestyle. This is the number everyone is chasing.

Retire Early (RE) is what you choose to do with it. Some people stop working entirely. Others pivot to passion projects, part-time work, or volunteering. The point is that you're choosing how to spend your time rather than selling it.

Many people in the FIRE community care far more about the FI part than the RE part.

The Core Math: The 25x Rule

The most widely-used framework for calculating your FI number is called the 25x rule:

Your FI Number = Annual Spending × 25

If you spend $60,000 per year, you need $1,500,000 invested. Spend $40,000? Your number is $1,000,000.

The 25x rule comes directly from the 4% safe withdrawal rate — the idea that you can withdraw 4% of your portfolio each year without running out of money over a 30-year retirement. (More on the research behind this in Safe Withdrawal Rates.)

Why FI Matters Even If You Love Your Job

Financial independence doesn't require retiring. Many people pursue FIRE specifically for the optionality it provides:

Take a lower-paying job you find more meaningful
Start a business without financial pressure
Take extended leave to care for family
Walk away from a toxic work situation without scrambling
Negotiate from a position of strength

"FU money" is a crude but accurate description of what FI gives you: the ability to say no.

FIRE Isn't Only for High Earners

A common misconception is that FIRE requires a tech salary. It doesn't. The ratio that matters is the gap between what you earn and what you spend. A household earning $80,000 and saving $30,000 per year is on a faster FIRE timeline than one earning $200,000 and saving $30,000 per year.

Income accelerates the journey. But your savings rate — the percentage of income you save — is the variable that most determines when you reach FI.

What FIRE Doesn't Mean

It doesn't mean stopping work forever. Most people who reach FI continue doing some kind of productive work — just on their own terms.
It doesn't require extreme frugality. There's a spectrum from bare-bones LeanFIRE to comfortable FatFIRE. You define your spending target.
It's not just for young people. Starting at 40 or 50 is still worth it — the benefits of FI compound in quality of life, not just portfolio value.

Try It Yourself

The best way to understand FIRE is to see your own numbers. Run your projection →