FIRE Number Calculator
Calculate how much you need to reach financial independence — and how many years until you get there.
| Extra Monthly Savings | New Monthly Total | Years to FIRE | Years Saved |
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What is FIRE?
FIRE stands for Financial Independence, Retire Early. The movement centers on saving aggressively — often 40–70% of income — to build a portfolio large enough to sustain living expenses indefinitely without paid work. The "retire early" part is optional; many FIRE adherents simply value having the option, not necessarily quitting work entirely.
The Math Behind the 25x Rule
The 25x rule comes directly from the 4% safe withdrawal rate. If you can safely withdraw 4% per year, you need 1/0.04 = 25 times your annual expenses. Spend $40,000/year? You need $1,000,000. Spend $80,000/year? You need $2,000,000. It's a clean heuristic derived from historical stock market data, though actual sustainability depends on sequence of returns, asset allocation, and flexibility in spending.
Why Savings Rate Matters More Than Income
Two key variables drive years to FIRE: savings rate and investment returns. Someone earning $150,000 and saving 10% reaches FIRE far later than someone earning $70,000 and saving 50%. A higher savings rate compresses time to FIRE from two directions — it adds more to the portfolio each year and reduces the FIRE number (since lower spending means less portfolio needed). This is why the FIRE community focuses intensely on spending efficiency.
Common FIRE Criticisms
FIRE strategies face legitimate challenges: sequence of returns risk is amplified by a 40–50 year retirement horizon (versus the 30 years the Trinity Study modeled); healthcare costs before Medicare eligibility at 65 can be substantial; and the psychological transition from accumulation to spending a portfolio can be difficult. Many early retirees find they continue to earn some income through passion projects or consulting, which dramatically improves their financial security.