FIRE Calculator — Financial Independence, Retire Early
Calculate how many years until you reach financial independence using the FIRE method. Enter current savings, monthly contribution, return rate, and annual expenses to get your FIRE number and a portfolio vs. target chart.
How to use this tool
- Enter current portfolio value, monthly savings, annual investment return, annual expenses in retirement and safe withdrawal rate in the fields above.
- Results update instantly as you type — or click Calculate.
- Read your years to fire and the full breakdown beneath it.
FIRE stands for Financial Independence, Retire Early. The core formula: accumulate 25x your annual expenses (assuming a 4% safe withdrawal rate). Once your portfolio hits that number, you can live off investment returns indefinitely.
FIRE Number: Annual Expenses ÷ Safe Withdrawal Rate
⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.
Formula
FIRE Number: FIRE Number = Annual Expenses / Safe Withdrawal Rate
Portfolio grows each month at monthly rate i = r / 12: Balancem+1 = Balancem × (1 + i) + Monthly Savings
FIRE is reached when Balance ≥ FIRE Number.
How it works
The calculator derives your target portfolio size by dividing projected annual retirement expenses by the chosen safe withdrawal rate — the classic 25× rule at 4% SWR. It then simulates month-by-month portfolio growth from your current balance plus monthly contributions at the specified annual return, counting months until the portfolio crosses the FIRE number.
The model assumes a constant nominal return and does not account for inflation, taxes, or variable spending. The safe withdrawal rate is a research-based guideline, not a guarantee; actual longevity of a portfolio depends on sequence-of-returns risk and market conditions.
Worked example
- Current portfolio: $0. Monthly savings: $100,000. Annual return: 0%. Annual expenses: $40,000. Safe withdrawal rate: 4%.
- FIRE Number = $40,000 / 0.04 = $1,000,000.
- With 0% return and $100,000 added each month, after 10 months the balance reaches $1,000,000.
FIRE reached in 10 months (FIRE number: $1,000,000).
Common mistakes to avoid
- Using a 4% withdrawal rate for retirements longer than 30 years — many FIRE practitioners use 3-3.5% for 40-50-year retirements to reduce sequence-of-returns risk.
- Entering gross salary as the saving rate instead of net after taxes and fixed expenses, inflating monthly contributions and shortening the projected FIRE date.
- Assuming post-FIRE expenses equal current expenses without adjusting for healthcare costs (no employer coverage) or reduced work-related spending.
Key terms
- FIRE
- Financial Independence, Retire Early — a movement centred on accumulating enough invested assets to live indefinitely off investment returns.
- Safe withdrawal rate (SWR)
- The percentage of a portfolio withdrawn annually that historical data suggests will not deplete the portfolio over a 30-year retirement; commonly cited as 4%.
- FIRE Number
- The total portfolio value needed to retire, calculated as annual expenses divided by the safe withdrawal rate.
- Sequence-of-returns risk
- The danger that poor market returns early in retirement permanently reduce portfolio longevity, even if long-run average returns are acceptable.
- Portfolio
- The total value of invested assets accumulated toward financial independence.
Frequently asked questions
- What is the safe withdrawal rate?
- Research (the 'Trinity Study') suggests a 4% withdrawal rate historically survived 30+ year retirement periods. More conservative retirees use 3-3.5%.
- What is Lean FIRE vs. Fat FIRE?
- Lean FIRE targets minimal expenses (~$25-40k/yr). Fat FIRE targets a comfortable lifestyle ($80-100k+/yr). Choose based on your target lifestyle.