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FIRE Number Calculator — Find Your Financial Freedom Date

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Financial Independence · Retire Early

FIRE Number Calculator

Find your exact financial freedom date. See three paths to retirement, your real progress, and what one small change does to your timeline.





Target Retirement Age
45

35455565+

⚙️ Advanced settings
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What Is the FIRE Number and Why Does It Matter?

FIRE stands for Financial Independence, Retire Early. Your FIRE number is the total amount of invested capital you need so that a 4% annual withdrawal covers your living expenses indefinitely. This rule, derived from the Trinity Study at Trinity University, is based on historical stock market data showing that a diversified portfolio can sustain a 4% withdrawal rate for at least 30 years in virtually all historical scenarios.

The formula is simple: FIRE Number = Annual Expenses divided by 0.04, or equivalently Annual Expenses multiplied by 25. If you spend $40,000 per year, your FIRE number is $1,000,000. Once you reach that number with your invested assets, you can theoretically live off the portfolio returns without ever depleting the principal.

Lean FIRE, Regular FIRE, and Fat FIRE

Lean FIRE means retiring on a reduced budget — typically 70% of current expenses — accepting a more frugal lifestyle in exchange for reaching financial independence much earlier. Regular FIRE targets your current spending level. Fat FIRE aims for 150% or more of current expenses, providing a generous buffer for travel, healthcare, and lifestyle upgrades in retirement.

What Is Coast FIRE?

Coast FIRE is the point at which your current savings, left untouched, will grow to your full FIRE number by your target retirement age through compound interest alone. Once you reach Coast FIRE, you no longer need to save aggressively — you just need to cover your current living expenses with your income, and time does the rest of the work.

The 4% Rule — Is It Still Valid?

The 4% safe withdrawal rate comes from the 1994 Trinity Study and has been widely discussed and debated. In historical back-tests, a portfolio of 50-75% stocks never ran out of money over a 30-year retirement period when withdrawing 4% annually. Some researchers suggest a 3-3.5% rate for longer retirements (40+ years), while others argue 4-4.5% remains reasonable with a flexible spending approach.

Frequently Asked Questions

How much should I be saving each month?
Your savings rate is the single most powerful lever in the FIRE equation. A savings rate of 50% or more can lead to financial independence in 15-17 years from any starting point. Even increasing from 10% to 20% can shave a decade off your timeline. Focus on increasing income and reducing fixed expenses for the biggest impact.

What investment return should I assume?
The US stock market has historically returned about 10% nominally and 7% after inflation over long periods. For a diversified global portfolio, 6-8% nominal or 3-5% real (after inflation) is a reasonable conservative assumption. This calculator uses real returns by subtracting your inflation assumption from the nominal return.

Does the FIRE Number account for Social Security or pension income?
This calculator focuses on the pure FIRE number based on your expenses. If you expect Social Security, pension, or rental income in retirement, you can reduce your monthly expenses input by the expected monthly income from those sources to get a more accurate picture.

What is the difference between nominal and real returns?
Nominal return is the raw percentage your investments grow. Real return is nominal minus inflation — it represents your actual increase in purchasing power. If your portfolio grows 8% but inflation is 3%, your real return is approximately 5%. This calculator uses real returns so all figures are expressed in today’s purchasing power.

Can I really retire early with this approach?
Yes, thousands of people have achieved financial independence through disciplined saving and investing in index funds. The math works regardless of income level — it is about the gap between income and expenses, not the absolute numbers. A high earner who spends everything will never reach FIRE; a moderate earner who saves 40% can reach it in under 25 years.

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