FIRE Calculator — Financial Independence, Retire Early

The Math of FIRE

FIRE rests on the 4% rule from the Trinity Study: a 60/40 portfolio of equities and bonds has historically supported a 4% inflation-adjusted withdrawal rate over 30-year retirements with very high success rates.

Inverting that: corpus required = annual expenses ÷ 4% = annual expenses × 25. Spend $40,000/year? You need $1M. Spend $80,000/year? You need $2M. There is no shortcut.

Variants of FIRE

• Lean FIRE — minimalist living. ~20× expenses. Often $500K–$1M total.
• Regular FIRE — 25× expenses, the canonical 4% rule. Most common variant.
• Fat FIRE — comfortable, no compromises. 33× expenses for safety + lifestyle inflation.
• Coast FIRE — save aggressively until your portfolio is big enough that, with zero more saving, it grows into a regular retirement number by age 60–65. After Coast FIRE, you can quit, downshift, or just stop saving.
• Barista FIRE — quit the high-stress job, take a part-time job for healthcare and partial expenses, let the portfolio grow.

The One Number That Matters: Savings Rate

FIRE is famously not about earning more — it’s about your savings rate (savings ÷ take-home). The math (assuming you earn 5% real return after inflation):

• 10% savings rate → 51 years to FIRE
• 25% savings rate → 32 years to FIRE
• 50% savings rate → 17 years to FIRE
• 65% savings rate → 11 years to FIRE
• 75% savings rate → 7 years to FIRE

Worked Example