FIRE Calculator

FIRE stands for Financial Independence, Retire Early—a lifestyle movement focused on saving aggressively to retire decades before traditional retirement age. The calculator determines your FIRE number by dividing annual expenses by your safe withdrawal rate (typically 4%). For example, $40,000 annual expenses ÷ 0.04 = $1,000,000 FIRE number. It then projects how long until your investments reach this target based on current savings, savings rate, and expected returns.

The 4% rule comes from the Trinity Study, which found that withdrawing 4% of your portfolio in the first year of retirement (adjusting for inflation thereafter) has historically sustained a portfolio for 30+ years with over 95% success rate. This means you need 25× your annual expenses saved. Some prefer a more conservative 3.5% rate (requiring 28.6× expenses) or a more aggressive 4.5% rate (22.2× expenses) depending on retirement length and risk tolerance.

Lean FIRE means retiring on a minimal budget—typically under $40,000/year for a single person—requiring less savings but a frugal lifestyle. Fat FIRE targets a comfortable or luxury retirement with $100,000+ annual spending, requiring a much larger nest egg. Coast FIRE is when you've saved enough that compound growth alone will reach your FIRE number by traditional retirement age, so you only need to cover current expenses without additional saving. Standard FIRE falls in between, typically covering moderate expenses.

Your FIRE number = Annual Expenses ÷ Safe Withdrawal Rate. First, track your actual spending for several months to determine accurate annual expenses. Include all costs: housing, food, healthcare, insurance, taxes, entertainment, and a buffer for unexpected expenses. Then divide by your chosen withdrawal rate: at 4%, multiply expenses by 25; at 3.5%, multiply by 28.6. If you spend $50,000/year and use 4%, your FIRE number is $1,250,000.

The two most powerful levers are: 1) Increase savings rate—going from 20% to 50% savings rate can cut years to FIRE from 37 to 17 years. 2) Reduce expenses—this double-dips by both increasing savings AND lowering your FIRE number. Other strategies include increasing income through career growth or side hustles, house hacking (renting part of your home), tax optimization (maxing 401k, HSA, Roth IRA), and geographic arbitrage (living in lower cost areas). A 70%+ savings rate can achieve FIRE in under 10 years.