How to Retire Early with Index Funds: The Complete FIRE Guide

What Is the FIRE Movement?

FIRE stands for Financial Independence, Retire Early. It's a lifestyle and financial philosophy focused on achieving financial independence — having enough invested assets to live on indefinitely without working — as quickly as possible, often decades before traditional retirement age.

Index funds are the investment vehicle of choice for the vast majority of FIRE practitioners. Their low costs, diversification, and historical returns make them ideal for the decades-long wealth accumulation the strategy requires.

The Math Behind FIRE

FIRE rests on a simple mathematical relationship: your savings rate determines how many years until you achieve financial independence. Based on the 4% safe withdrawal rate rule:

• Saving 10%: ~43 years to FIRE
• Saving 25%: ~32 years
• Saving 50%: ~17 years
• Saving 65%: ~10.5 years
• Saving 75%: ~7 years

How Much Do You Need?

The basic FIRE formula: multiply your annual expenses by 25. This gives you your "FIRE number" — the portfolio size that can sustainably fund your lifestyle indefinitely.

• $30,000/year expenses → $750,000 FIRE number
• $50,000/year expenses → $1,250,000
• $80,000/year expenses → $2,000,000
• $100,000/year expenses → $2,500,000

The Index Fund FIRE Portfolio

Most FIRE practitioners use simple, low-cost index fund portfolios:

• Simple: 100% VTI (Vanguard Total Market ETF) or FZROX (Fidelity)
• Two-fund: 80% VTI + 20% VXUS (international)
• Three-fund: 60% VTI + 20% VXUS + 20% BND (bonds)

FIRE Variations

• LeanFIRE: Extreme frugality, retire with a smaller portfolio and lower expenses
• FatFIRE: Accumulate a larger portfolio for a more comfortable retirement lifestyle
• BaristaFIRE: Partially retire, work part-time for enjoyment or health insurance
• CoastFIRE: Save enough early that compound growth handles the rest — then work only for current expenses