FIRE Calculator

About the FIRE Calculator

A FIRE calculator (Financial Independence, Retire Early calculator) determines your FIRE number — the portfolio size you need to retire and live indefinitely off investment returns — and calculates how many years it will take to reach that number given your current savings rate, investment returns, and annual spending. FIRE is a financial movement focused on aggressive saving and investing to achieve financial independence decades earlier than the traditional retirement age. The core mathematical principle is the 4% safe withdrawal rule: a diversified investment portfolio can sustain annual withdrawals of 4% of its starting balance indefinitely, meaning your FIRE number is 25 times your anticipated annual expenses. Our free FIRE calculator models your path to financial independence, lets you explore different savings rate and spending scenarios, and shows how adjusting each variable affects your FIRE timeline.

How It Works

FIRE number = Annual expenses x 25 (the inverse of the 4% rule). Example: target $50,000/year in early retirement: FIRE number = $50,000 x 25 = $1,250,000. If you have $200,000 saved and invest $3,000/month at 7% real (inflation-adjusted) return: FV = 200,000 x (1.07)^n + 3,000 x 12 x [((1.07)^n - 1)/0.07] = $1,250,000. Solving: approximately 12.8 years to FIRE. Savings rate determines FIRE timeline more than almost any other factor: at a 50% savings rate, most people reach FIRE in 15-17 years regardless of income. At 10% savings rate: 40+ years. The FIRE calculator explores Lean FIRE (below-average spending), regular FIRE, Fat FIRE (above-average spending), and Coast FIRE (stop contributing and let existing savings grow to FIRE number).

Tips & Best Practices

• ✓The 4% rule is based on the Trinity Study (1998) examining 30-year retirement periods using US historical market data. For early retirement lasting 40-50 years, a more conservative 3.25-3.5% withdrawal rate (multiply expenses by 28-31) provides additional safety.
• ✓Savings rate is the dominant variable: going from 20% to 50% savings rate can cut your FIRE timeline by 15-20 years — far more impactful than optimising investment returns by 1-2%.
• ✓Geographic arbitrage: retiring to a lower cost-of-living country reduces your FIRE number dramatically. A $30,000/year lifestyle in Southeast Asia or Mexico requires $750,000 versus $1,500,000 for a $60,000/year lifestyle in a high-cost US city.
• ✓Healthcare planning for early RETIREES (USA): before Medicare eligibility at 65, early retirees must independently source health insurance. ACA marketplace plans with premium tax credits (available at incomes below 400% of poverty line) can cost $0-200/month with careful income planning.
• ✓Social Security still accrues for early retirees: if you worked for 10+ years, you will receive reduced Social Security benefits at 62 or full benefits at 67. This additional income source allows a smaller FIRE portfolio than calculations omitting it suggest.
• ✓Sequence of returns risk: retiring into a market downturn (like 2000 or 2008) can permanently impair a portfolio even with an adequate FIRE number. The 4% rule already accounts for this historically, but holding 2-3 years of cash reserves provides additional buffer.
• ✓Coast FIRE: if you have enough invested that it will grow to your full FIRE number by traditional retirement age (65) without any additional contributions, you have reached Coast FIRE — you can stop investing and only need to cover current expenses.
• ✓Fat FIRE versus Lean FIRE: Lean FIRE targets minimal spending (often $25,000-40,000/year). Regular FIRE is $40,000-80,000/year. Fat FIRE typically means $100,000+/year. The three categories have FIRE numbers ranging from $625,000 to $2,500,000+.

Who Uses This Calculator

High-income earners with high savings rates planning to retire in their 30s or 40s. People who want to understand how many years of aggressive saving it takes to achieve financial independence. Those questioning whether their current spending and savings rate will ever lead to retirement. People exploring how changing their lifestyle — reducing expenses, increasing income, or both — affects the FIRE timeline. Financial bloggers and coaches educating clients about the mathematical relationship between savings rate and retirement timeline.