FIRE Number Calculator
Based on the 4% rule · Updated 2026
What Is a FIRE Number?
Your FIRE number is the total amount of invested assets you need to achieve financial independence and retire early. It represents the point where your portfolio can sustainably generate enough income to cover your living expenses indefinitely.
The concept comes from the 4% rule, introduced in the landmark Trinity Study (Cooley, Hubbard & Walz, 1998). By dividing your annual expenses by your safe withdrawal rate, you get a target number. For most people using a 4% withdrawal rate, this means saving 25 times your annual expenses.
How Your FIRE Number Is Calculated
The core formula is simple: FIRE Number = Annual Expenses ÷ Withdrawal Rate. For $40,000 in annual spending at a 4% withdrawal rate, your FIRE number is $1,000,000.
But this calculator goes further. It factors in your current savings, savings rate, and expected investment returns to give you a personalized timeline — not just the target, but how long it will take to reach it.
| Withdrawal Rate | Multiplier | FIRE Number |
|---|---|---|
| 3.0% | 33.3× | $1,333,333 |
| 3.5% | 28.6× | $1,142,857 |
| 4.0% | 25× | $1,000,000 |
| 4.5% | 22.2× | $888,889 |
| 5.0% | 20× | $800,000 |
Factors That Affect Your Timeline
Savings rate is the single biggest lever. Someone saving 50% of their income reaches FI in roughly 17 years; someone saving 20% takes about 37 years.
Investment returns compound powerfully over time. A 1% difference in annual returns can change your timeline by 3-5 years.
Your current savings give you a head start. Even $50,000 invested at age 30 can shave 3-4 years off your journey compared to starting from zero.
| Savings Rate | Years to FI | Retirement Age (if starting at 25) |
|---|---|---|
| 20% | 37 years | 62 |
| 30% | 28 years | 53 |
| 40% | 22 years | 47 |
| 50% | 17 years | 42 |
| 60% | 12.5 years | 37 |
| 70% | 8.5 years | 33 |
What to Do After Getting Your Number
1. Track your expenses — your FIRE number is only as accurate as your expense estimate. Use a budgeting tool for 6-12 months before committing to a number.
2. Invest in low-cost index funds — VTI, VOO, or VT are the standard recommendations. Keep expense ratios under 0.10%.
3. Maximize tax-advantaged accounts — 401(k), IRA, HSA first, then taxable brokerage.
4. Recalculate annually — inflation, lifestyle changes, and market returns will shift your number over time.
Frequently Asked Questions
How is fire number calculator calculated?
The formula is: Annual Expenses ÷ Withdrawal Rate. Enter your values above and click Calculate to see your personalized result instantly. Your FIRE number is the amount you need invested for financial independence. Based on the 4% rule: FIRE Number = Annual Expenses × 25. For $40,000 annual expenses, you need $1,000,000 invested. This…
What inputs do I need for the fire number calculator?
You need: Expenses, Savings Rate, Current Age, Current Savings, Expected Return, Withdrawal Rate. Default values are pre-filled — adjust them to match your personal finances for a customized result.
Is the fire number calculator free to use?
Yes — all TorchFI calculators are completely free. No registration, no email required. Calculations run entirely in your browser for maximum privacy. We never see or store your financial data.
How does the fire number calculator help with FIRE planning?
Calculate the total amount you need invested to reach financial independence using the 4% rule. Factors in your savings rate, current age, and expected returns to give a personalized timeline to FI. This calculator helps you make data-driven decisions about your financial independence journey instead of relying on guesswork.