FIRE Calculator

Your FIRE number is the total invested assets you need to retire and live off your portfolio indefinitely. It is calculated by multiplying your expected annual spending in retirement by 25 — the inverse of the 4% safe withdrawal rate. If you plan to spend $50,000 per year in retirement, your FIRE number is $1,250,000. If you plan to spend $80,000, your FIRE number is $2,000,000. This rule assumes your portfolio will generate at least 4% real returns annually to sustain indefinite withdrawals.

The three FIRE variants reflect different lifestyle spending targets. Lean FIRE uses a 5% withdrawal rate (20x annual spending) — designed for a minimalist lifestyle, typically $25,000 to $40,000 per year. Regular FIRE uses the standard 4% rate (25x spending) for a comfortable middle-class lifestyle. Fat FIRE uses a 3% withdrawal rate (33x spending) for a generous lifestyle with significant discretionary spending, typically $100,000 per year or more. Barista FIRE is a hybrid — partially funded portfolio plus a low-stress part-time job to cover daily expenses while the portfolio continues to grow.

Coast FIRE is the point at which your existing invested assets — without any additional contributions — will grow to your full FIRE number by your target retirement age through compound interest alone. Once you reach Coast FIRE, you only need to earn enough to cover your current living expenses — you can "coast" to retirement without saving another dollar. For example, $200,000 invested at age 35 growing at 7% annually reaches approximately $1.5 million by age 65 — if that's your FIRE number, you've hit Coast FIRE at 35.

The historical average real return of the U.S. stock market is approximately 7% after inflation. FIRE calculators typically use 7% as a default because it is a long-term average that accounts for both bull and bear markets. More conservative planners use 5% to account for potentially lower future returns or a more conservative asset allocation. More aggressive FIRE seekers sometimes use 8% or 9% for the accumulation phase. The withdrawal phase typically uses a lower assumed return — 4% to 5% — reflecting a more conservative allocation in retirement.

Inflation erodes purchasing power over time. A $50,000 lifestyle today will cost approximately $90,000 in 20 years at 3% annual inflation. Most FIRE calculations account for inflation by using real (inflation-adjusted) returns rather than nominal returns. The 4% safe withdrawal rate was derived from historical data that already accounts for inflation — meaning the 4% withdrawal is increased annually to maintain purchasing power. If you retire at 40 instead of 65, your portfolio needs to sustain 50+ years of withdrawals rather than the 30 years the 4% rule was designed for, which is why many early retirees use a 3% or 3.5% rate.

Yes — but carefully. If you are pursuing early retirement before Social Security eligibility (age 62 earliest, with FRA at 67), you cannot count on Social Security for the early years. Your FIRE number must fund those years independently. Once you reach Social Security claiming age, your monthly benefit reduces the amount your portfolio must support. A $2,000 monthly Social Security benefit reduces your annual portfolio withdrawal need by $24,000 — reducing your required FIRE number by $600,000 (at the 4% rate) for the period when you receive benefits.

The original 4% safe withdrawal rate was based on a 30-year retirement period. For early retirees targeting 40 to 50 year retirements, most research suggests a 3% to 3.5% withdrawal rate provides better protection against sequence-of-returns risk. The Trinity Study (the academic basis for the 4% rule) showed 4% had a 95% success rate over 30 years but a lower success rate over 40+ years. For a 50-year retirement, 3.3% is commonly cited as the equivalent safe rate. The calculator above allows you to model any withdrawal rate from 3% to 5% to see how it affects your longevity projection.