🔥 FIRE Calculator
Find your FIRE number using the 4% rule, project your savings growth with compound returns, and discover the exact age you could reach financial independence.
How the FIRE Number and the 4% Rule Work
FIRE — Financial Independence, Retire Early — is the movement built on one powerful idea: once your investments can cover your living expenses indefinitely, work becomes optional. This calculator tells you exactly how much you need and when you'll get there.
What Is the FIRE Number?
Your FIRE number is the portfolio size that makes you financially independent. It comes from the 4% rule, based on the Trinity Study: a retiree withdrawing 4% of their portfolio per year (adjusted for inflation) historically did not run out of money over 30-year retirements. The formula is simple:
Example: $60,000 ÷ 0.04 = $1,500,000
Worked Example
A 35-year-old has $100,000 invested, contributes $20,000/year, earns 7% annually, and spends $60,000/year. FIRE number = $60,000 ÷ 0.04 = $1,500,000. Compound growth: FV = $100,000×(1.07)25 + $20,000×[((1.07)25−1)/0.07] ≈ $1,807,700 by age 60 — about $307,700 past the FIRE number. Solving backwards, this saver actually crosses $1.5M at roughly age 57.6, more than two years before the target.
How to Use This Calculator
Enter your current age, savings, yearly contributions, and expected return. The calculator projects your portfolio with the future-value-of-annuity formula, compares it to your FIRE number, and binary-searches the exact age your savings cross the target. Raise contributions or expected return and watch your FI age drop — small increases compound enormously over 20+ years. Note the 4% rule assumes a stock-heavy portfolio and a ~30-year retirement; earlier retirees often use 3.5% for extra safety.
Beyond the 4% Rule
The 4% rule assumes a 30-year retirement, ~50/50 stock-bond mix, and inflation-adjusted withdrawals. Early retirees face 50–60 year horizons, where sequence-of-returns risk — a bear market in your first five years — does the most damage. Mitigations: a larger bond tent near retirement, flexible withdrawals (cut spending 10–20% in down years), and part-time income. Variants worth knowing: Coast FIRE (save enough early that compounding alone hits your number, then work for expenses), Barista FIRE (semi-retire with benefits-providing part-time work), and Fat FIRE ($2.5M+ for higher spending). Budget healthcare explicitly — pre-Medicare insurance can run $500–$1,500/month per person. Fees and taxes are silent killers: a 1% advisory fee over 40 years can consume nearly a third of potential wealth, so prefer low-cost index funds in tax-advantaged accounts first.
Frequently Asked Questions (FAQs)
What is the 4% rule?
The 4% rule comes from the Trinity Study (1998): withdrawing 4% of your portfolio in year one of retirement, then adjusting for inflation each year, historically survived 30-year retirements in most market scenarios. It implies you need 25× your annual expenses invested.
What is a good FIRE number?
It depends entirely on spending. At $40,000/year expenses, your FIRE number is $1,000,000; at $80,000/year it is $2,000,000. Cutting expenses is the highest-leverage move because it shrinks the target AND speeds up savings.
Is the 4% rule still safe in 2026?
Many planners now suggest 3.5–4% as a starting point, with flexibility to cut spending in down years. Early retirees (40+ year horizons) often target 3–3.5% for extra margin. This calculator lets you adjust the withdrawal rate.
What return should I assume?
US stocks have returned ~10% nominal (~7% after inflation) long-term. A 7% nominal assumption is common for stock-heavy portfolios; use 5–6% to be conservative or if you hold bonds.
What are Lean FIRE and Fat FIRE?
Lean FIRE means retiring on minimal spending (often under $40k/year); Fat FIRE targets a higher-spending lifestyle ($100k+/year) and a larger portfolio. Coast FIRE is the middle path: save enough early that compounding alone reaches your number by traditional retirement age.
Last updated: September 2026
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Last updated: September 2026