Question 1

What is the FIRE number?

Accepted Answer

Your FIRE number is the portfolio size at which you can retire and live indefinitely off investment returns. It's calculated as Annual Expenses ÷ Safe Withdrawal Rate. At a 4% SWR, you need 25× your annual expenses. For $40,000/year spending, that's a $1,000,000 FIRE number.

Question 2

Is the 4% rule still valid?

Accepted Answer

The 4% rule comes from the Trinity Study (1998), which analyzed historical 30-year retirement periods using a 50/50 stock-bond portfolio. It found a 95%+ success rate. For early retirees with 40-50 year horizons, many experts recommend 3.5% (28.5× expenses) or 3% (33× expenses) to account for longer withdrawal periods.

Question 3

What types of FIRE exist?

Accepted Answer

Lean FIRE: Early retirement on $25,000–$40,000/year with frugal living. Regular FIRE: Retirement on $50,000–$80,000/year. Fat FIRE: Retiring on $100,000+/year with lifestyle flexibility. Coast FIRE: Investing enough early so compound growth alone funds retirement. Barista FIRE: Semi-retirement with part-time income supplementing a smaller portfolio.

Question 4

What investment return should I use for FIRE projections?

Accepted Answer

7% is the most commonly recommended inflation-adjusted annual return for a diversified index fund portfolio, based on the S&P 500's long-term historical average of ~10% minus ~3% inflation. Conservative planners use 5–6%; more aggressive projections use 8–9%. The actual return will vary year to year, but 7% is a reasonable long-term planning assumption.

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