Your savings rate matters most
The share of your income you save decides how fast you reach financial independence, because it both grows your investments and lowers the amount you need. Starting from zero, with a 5% real return and the 4% rule, saving 10% of take-home pay takes over 50 years, 25% takes about 32 years, 50% about 17 years and 75% about 8 years. The table in the calculator shows this for your numbers.
The math
FIRE number = yearly spending ÷ withdrawal rate
Each year: investments × (1 + real return) + yearly savings
The calculator repeats the second line until your investments reach your FIRE number. Coast FIRE is the amount you would need invested today so that growth alone, with no more saving, reaches your FIRE number by your traditional retirement age.
Ways to reach FIRE faster
- Cut the big three costs: housing, transportation and food.
- Grow income through raises, job changes or a side business.
- Invest in low-cost index funds and use tax-advantaged accounts like a 401(k) and an IRA.
- Plan health insurance and early-withdrawal rules before leaving work.
Track your progress with the net worth calculator and set spending targets with the budget calculator.
Last reviewed October 2026.
Frequently asked questions
What is FIRE?
FIRE stands for Financial Independence, Retire Early. The idea is to save and invest a large share of your income until your investments can cover your living costs, so working becomes optional, often decades before the usual retirement age.
How is the FIRE number calculated?
Your FIRE number is your yearly spending divided by your safe withdrawal rate. With the common 4% rule, that is 25 times your annual expenses. If you spend $40,000 a year, your FIRE number is $1,000,000.
Is the 4% rule safe for early retirement?
The 4% rule comes from studies of 30-year retirements. For retirements of 40 to 50 years, many planners suggest 3.25% to 3.5% to be safer. You can set your own withdrawal rate in the calculator.
Why does the calculator use a real return?
A real return is your investment return minus inflation, for example 7% minus 3% inflation = 4% real. Using it keeps everything in today's dollars, so your FIRE number and savings stay comparable over time.
What are Lean FIRE, Fat FIRE and Coast FIRE?
Lean FIRE means retiring on a small budget. Fat FIRE means a comfortable or generous budget, needing a bigger portfolio. Coast FIRE means you have saved enough that, with no more contributions, growth alone will reach your target by traditional retirement age.