FIRE Number Calculator
The FIRE (Financial Independence, Retire Early) movement uses the 4% safe withdrawal rule to define a target portfolio size. Calculate yours instantly.
Understanding Your FIRE Number
Financial Independence, Retire Early (FIRE) is a movement built around the idea that aggressive saving and investing can allow you to stop working far earlier than the traditional retirement age of 65. The core concept is simple: accumulate a portfolio large enough that its investment returns can sustainably fund your lifestyle indefinitely, without you ever needing to work again.
The 4% rule is the mathematical backbone of FIRE. If your annual retirement spending is $50,000, you need $1.25 million (50,000 ÷ 0.04). At a 7% average annual return with 3% inflation, a 4% withdrawal rate leaves the portfolio growing in real terms — your money outlasts you rather than running out. Reaching your FIRE number is the finish line.
FIRE Numbers by Annual Spending Level
| Annual Expenses | FIRE Number (4%) | Conservative (3.5%) | FIRE Type |
|---|---|---|---|
| $30,000 | $750,000 | $857,000 | Lean FIRE |
| $40,000 | $1,000,000 | $1,143,000 | Lean FIRE |
| $50,000 | $1,250,000 | $1,429,000 | Regular FIRE |
| $60,000 | $1,500,000 | $1,714,000 | Regular FIRE |
| $75,000 | $1,875,000 | $2,143,000 | Fat FIRE |
| $100,000 | $2,500,000 | $2,857,000 | Fat FIRE |
How to Reach FIRE Faster
The single most powerful lever is your savings rate. Someone saving 10% of income might need 40+ years to reach FIRE. Someone saving 50% might reach it in 15–17 years. Someone saving 70–75% can reach financial independence in under 10 years, regardless of income level. The math works because high savings rates both accelerate portfolio growth and reduce the FIRE number (lower expenses = smaller target).
Tax-advantaged accounts — 401(k), IRA, HSA — accelerate the journey by reducing your tax burden and keeping more money working. The order of operations: max your 401(k) match first (free money), then HSA if eligible, then Roth IRA, then remaining 401(k) space, then taxable brokerage. This sequence minimizes lifetime taxes on your path to FIRE.
Frequently Asked Questions
What is the 4% rule?
The 4% rule comes from the Trinity Study (1998), which analyzed historical US stock and bond returns from 1926–1995. It found that a portfolio invested 50/50 in stocks and bonds survived 30 years of withdrawals at a 4% initial rate in 95% of historical scenarios. It became the foundational safe withdrawal rate for retirement planning, though some researchers now suggest 3.3–3.5% for longer retirements.
What is a FIRE number?
Your FIRE number is the total portfolio value you need to retire sustainably. It is calculated as: Annual Expenses ÷ Withdrawal Rate. At the 4% rule, your FIRE number is 25x your annual expenses. Someone spending $50,000/year needs $1.25 million. Someone spending $80,000/year needs $2 million. The FIRE number assumes your portfolio grows at roughly the same rate you withdraw, allowing it to last indefinitely.
Is 4% still safe for early retirement?
The 4% rule was designed for 30-year retirements. If you retire at 40 and plan for a 50+ year retirement, many FIRE practitioners use a more conservative 3–3.5% withdrawal rate, implying a FIRE number of 28–33x expenses. Sequence-of-returns risk — experiencing a major market crash early in retirement — is the main threat to any withdrawal strategy. A cash buffer or flexible spending helps mitigate this.
What are the FIRE variants?
Lean FIRE targets a frugal retirement budget (under $40,000/year), requiring a smaller portfolio and more aggressive saving. Fat FIRE targets a comfortable or affluent retirement (over $80,000–$100,000/year). Barista FIRE (or Coast FIRE) means retiring from full-time work while doing part-time work to cover current expenses, letting the existing portfolio grow untouched until full retirement age. Each variant adjusts the FIRE number and timeline significantly.