FI Number
Your FI number is the total amount you need invested so that your portfolio can sustain your annual spending indefinitely. It's the finish line for financial independence.
How to Calculate It
The simplest method: multiply your annual expenses by 25. If you spend $50,000/year, your FI number is $1,250,000. This is the inverse of the 4% rule: withdrawing 4% of $1.25M gives you $50,000/year.
Why Expense Multiples Are Better
Saying "I need $1.25 million" is less useful than saying "I'm at 14x annual expenses and need 25x." The multiplier works regardless of income level and makes progress feel tangible. Going from 14x to 15x is a clear milestone. Going from $700K to $750K feels abstract.
The FIRE community increasingly frames progress this way. As one highly-upvoted comment put it: "FIRE should be discussed as multiples of annual expenses. That's the whole point."
What Changes Your FI Number
Your FI number isn't fixed. It moves when your spending changes. Lifestyle inflation raises it. Moving to a lower cost-of-living area drops it. This is why tracking expenses matters as much as tracking investments. Reducing spending by $10,000/year lowers your FI number by $250,000.
Related Terms
The 4% Rule
The 4% rule is a retirement guideline that says you can withdraw 4% of your portfolio in your first year of retirement, then adjust for inflation each year, and your money should last at least 30 years.
Expense Multiple
An expense multiple is your portfolio value divided by your annual spending. If you have $700,000 saved and spend $50,000/year, you're at 14x. Financial independence using the 4% rule requires 25x.
Coast FIRE
Coast FIRE is the point where you've saved enough that your investments will grow to your full retirement number on their own, even if you never save another dollar.
This tool is for educational and informational purposes only. It does not constitute financial advice. Past performance does not guarantee future results. Consult a qualified financial advisor for personalized advice.