What is the difference between LeanFIRE and FatFIRE?

LeanFIRE covers essential, minimalist living expenses (typically 75% of average spend), while FatFIRE funds an abundant lifestyle with generous discretionary spending (140%+ of average spend).

Updated: August 2026 • Verified v1.2

FIRE Calculator — Financial Independence Retire Early

Finance & MathPopular

Local Browser Execution: Your input is processed locally in your browser and is not sent to UTL servers.

FIRE Target = Annual_Expenses / SWR_Rate; Real_Return = Return - Inflation

Was this calculation helpful?

Understanding Your Results

Calculates FIRE target number, LeanFIRE (frugal 75%), FatFIRE (luxury 140%), real inflation-adjusted investment return, and years/months to financial independence.

Practical Guidance & Next Steps

The 4% Safe Withdrawal Rule (from the Trinity Study) states you can safely withdraw 4% of your initial portfolio each year, adjusted for inflation, with near-zero historical failure over 30+ years.

What is this?

A wealth forecasting utility that computes your retirement number and timeline to Financial Independence.

How does it work?

1. Enter annual living expenses and current invested net worth. 2. Enter annual savings contributions and select Safe Withdrawal Rate (3.0% to 4.5%). 3. View your FIRE target number, Lean/Fat tiers, and estimated years to retirement.

Why use it?

Clarifies your exact freedom number and reveals how increasing savings rate dramatically cuts years off your career.

Technical Scope & Calculation Limitations

Calculates projections based on constant annual savings contributions and real average market returns.

Frequently Asked Questions

The 4% rule states that if you accumulate 25 times your annual living expenses in an investment portfolio, you can withdraw 4% annually without running out of money.

Windows Desktop & Widget Options