Question 1

What is the FIRE number and how do I calculate it?

Accepted Answer

Your FIRE number is the amount you need invested to retire — defined as 25× your annual expenses (based on the 4% safe withdrawal rate). If you spend $60,000/year: $60,000 × 25 = $1,500,000 FIRE number. At 4% withdrawal, $1,500,000 generates $60,000/year in income, and historical data suggests this portfolio has roughly 95% probability of lasting 30 years. The 4% rule comes from the Trinity Study using 1926–1995 US stock and bond data.

Question 2

Is the 4% rule still valid in 2026?

Accepted Answer

The 4% rule has held up historically but faces scrutiny at current valuations. Some planners advocate 3%–3.5% for longer retirements (40+ years) or those retiring in their 30s–40s. At 3.5%, your FIRE number on $60,000/year becomes $1,714,000 vs $1,500,000. The key variables: sequence of returns risk (bad markets in years 1–5 are most damaging), inflation rate, and actual portfolio allocation. A 60/40 stock-bond split with annual rebalancing is the standard assumption.

Question 3

What is the difference between Lean FIRE, FIRE, and Fat FIRE?

Accepted Answer

Lean FIRE: retiring on $40,000/year or less, requiring a frugal lifestyle. FIRE number: roughly $1,000,000. Regular FIRE: $50,000–$100,000/year in spending. FIRE number: $1,250,000–$2,500,000. Fat FIRE: $100,000+/year spending without financial stress. FIRE number: $2,500,000+. Chubby FIRE ($80,000–$120,000/year) sits between regular and fat. Which level you target depends entirely on your actual spending — build the budget first, then calculate the number.

Question 4

How long does it take to reach FIRE on an average income?

Accepted Answer

It depends almost entirely on your savings rate — not your income. On a $80,000 salary, saving 10% ($8,000/year) takes about 43 years to hit 25× $64,000 expenses. Saving 30% ($24,000/year) reduces expenses to $56,000 and takes about 28 years. Saving 50% ($40,000/year) reduces expenses to $40,000 and takes about 17 years. The math: higher savings rate simultaneously grows your portfolio faster and reduces the FIRE number (because lower expenses = lower FIRE number). Every 1% savings rate increase accelerates FIRE noticeably.

Question 5

What investment return should I assume for FIRE projections?

Accepted Answer

Most FIRE community planners use 7% nominal (roughly 4% real after inflation) for a broadly diversified stock portfolio. Conservative projections use 5%–6%. The actual S&P 500 historical average is about 10% nominal / 7% real. Using 7% nominal is reasonable for a 70%–80% equity allocation. For FIRE projections with a 30–40 year horizon, the real return (after inflation) matters most — use 4%–5% real return to be conservative.

Savings Rate	Years to FIRE (from zero)
10%	~43 years
25%	~32 years
50%	~17 years
65%	~11 years
75%	~7 years

FIRE Calculator

What You Should Know

Charts & Projections

Portfolio Mix

Growth Scenarios

Wealth Over Time

Overview

The Math Behind FIRE

Savings Rate Is Everything

Tax-Advantaged Accounts and FIRE

Frequently Asked Questions

Sources & Methodology

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