About this tool
What Is a FIRE Calculator?
A FIRE calculator determines when you can achieve Financial Independence and Retire Early by computing your FIRE Number (the portfolio size needed to sustain your lifestyle), years to reach it at your current savings rate, and Coast FIRE status. The foundational principle is the 4% Rule from the 1998 Trinity Study, which found that a diversified portfolio can sustain 4% annual withdrawals for 30+ years.
FIRE Number = Annual Expenses ÷ Withdrawal Rate
Example: $40,000 expenses ÷ 4% = $1,000,000 FIRE Number
FIRE Variants
| Variant | Annual Expenses | Description |
|---|---|---|
| Lean FIRE | Under $40,000 | Minimalist lifestyle, geographic arbitrage |
| Traditional FIRE | $40,000-$100,000 | Comfortable middle-class retirement |
| Fat FIRE | Over $100,000 | Premium lifestyle with travel, dining, hobbies |
| Coast FIRE | Any | Enough saved that compounding alone reaches FIRE number by 65 |
| Barista FIRE | Any | Partially FI — covers basics with part-time work for health insurance |
The 4% Rule
The 4% Rule comes from the 1998 Trinity Study by Philip Cooley, Carl Hubbard, and Daniel Walz. It found that a 60/40 stock/bond portfolio survived 30 years of 4% withdrawals in 95% of historical periods. For early retirees (40-50 year time horizons), many planners recommend 3.25-3.5% as a safer rate. Variable withdrawal strategies (like the Guyton-Klinger guardrails) can allow higher starting rates.
Practical Usage Examples
Traditional FIRE
Age 30, $100K saved, $80K income, $40K expenses, 7% return
FIRE Number: $1M, Years to FIRE: ~13, Age at FIRE: 43Step-by-Step Instructions
Step 1: Enter Current Age. Your current age determines how many years of growth your investments have.
Step 2: Enter Current Savings. Total investment portfolio value (retirement accounts + brokerage). Do not include home equity unless you plan to sell.
Step 3: Enter Income and Expenses. Net annual income (after tax) and total annual expenses. The difference is your annual savings.
Step 4: Set Return and Inflation. Expected investment return (7% historical for stocks) and inflation (3% historical average).
Step 5: Set Withdrawal Rate. The original Trinity Study used 4%. Conservative planners use 3-3.5% for early retirees with 40-50 year time horizons.
Step 6: Review Results. See your FIRE number, years to FI, Coast FIRE status, and detailed analysis.
Core Benefits
FIRE Number Calculation: Uses your annual expenses and safe withdrawal rate to determine the exact portfolio size needed to cover expenses indefinitely. Formula: FIRE Number = Annual Expenses ÷ Withdrawal Rate.
Coast FIRE Analysis: Calculates the portfolio value at which your investments will grow to your FIRE number by age 65 without additional contributions, using real (inflation-adjusted) returns.
Inflation-Adjusted Projections: Uses real returns (nominal return minus inflation) so your FIRE number reflects purchasing power in today's dollars.
Savings Rate Impact: Shows your savings rate percentage — the single most important variable in reaching FIRE, as proven by detailed analysis of historical market data.
Frequently Asked Questions
Your FIRE number is the total investment portfolio needed to cover your annual expenses indefinitely. It equals your annual expenses divided by your safe withdrawal rate. At 4% withdrawal: $40,000 expenses = $1,000,000 FIRE number. At 3.5%: $40,000 = $1,142,857.
The 4% rule was validated for 30-year retirement periods (the Trinity Study, 1998). For early retirees with 40-50 year horizons, many financial planners recommend 3.0-3.5% for extra safety margin, especially during low-yield environments.
Coast FIRE means you have enough saved that compound growth alone will reach your FIRE number by traditional retirement age (65) without additional contributions. After reaching Coast FIRE, you only need to earn enough to cover current expenses.
Lean FIRE targets under $40,000/year in expenses (minimalist lifestyle). Fat FIRE targets over $100,000/year (premium lifestyle). The FIRE number for Lean is typically $1M or less; Fat FIRE requires $2.5M+. Traditional FIRE falls in between.
At 4% withdrawal: multiply your annual expenses by 25. For $50,000/year expenses, you need $1,250,000. Starting at age 25 with $0, saving $3,000/month at 7% returns, you reach $1.25M around age 40.
Savings rate. A 50% savings rate means reaching FIRE in about 17 years regardless of income level. A 75% savings rate reaches FIRE in about 7 years. Increasing savings rate has a much bigger impact than increasing investment returns.
Only if you plan to sell your home and downsize or rent. Most FIRE calculations exclude primary residence equity because you need somewhere to live. Include rental property equity if it generates income.
The calculator uses real returns (nominal return minus inflation). A 7% return with 3% inflation gives 4% real growth. Your FIRE number is expressed in today's purchasing power, so you don't need to manually adjust for future inflation.
Pay off high-interest debt (credit cards, personal loans) before investing for FIRE. Low-interest debt (mortgage under 4-5%) can be maintained while investing, since investment returns historically exceed the debt interest rate.
No. All calculations run locally in your browser. Your income, expenses, savings, and portfolio data are never transmitted to any server or stored anywhere.