Find Your FIRE Number & When You Can Retire Early

How the FIRE Calculator Works

Your FIRE number is based on the 4% safe withdrawal rate (also called the 4% rule), derived from the Trinity Study. The formula is simple:

NetWorthCast goes beyond a simple calculator. It uses your actual assets, income, and expenses to project when your liquid net worth crosses the FIRE threshold — accounting for compound growth, inflation, and one-time events.

Types of FIRE

Lean FIRE

Reaching financial independence on a minimalist budget — typically under $40,000/year in expenses. Requires a FIRE number of ~$1M. Best for frugal individuals or those in low cost-of-living areas.

Fat FIRE

Financial independence with a comfortable lifestyle — typically $100,000+ per year. Requires $2.5M+. For those who want to maintain their current standard of living without compromise.

Coast FIRE

The point where your current investments will compound to your full FIRE number by traditional retirement age — even if you never invest another dollar. After reaching Coast FIRE, you only need to cover current expenses. Learn more about Coast FIRE.

Barista FIRE

Semi-retirement where you work a low-stress part-time job for health insurance and basic expenses, while your investments continue growing toward full FIRE.

What Makes NetWorthCast Different

Most FIRE calculators ask you to type in a few numbers and give a static answer. NetWorthCast is a full financial planning tool that:

• Tracks your real assets — liquid (cash, stocks, 401k) and illiquid (real estate, vehicles) with individual return rates
• Projects 30 years forward — compound growth per asset, income growth, expense inflation
• Shows exactly when you hit FIRE — interactive chart with the FIRE threshold line and crossing point
• Compares cost of living — see how relocating to a cheaper city accelerates your FIRE date
• Handles real-world events — bonuses, home purchases, car payments ending, job changes

The 4% Rule Explained

The 4% rule comes from the 1998 Trinity Study, which analyzed historical stock and bond returns. It found that withdrawing 4% of your portfolio annually (adjusted for inflation) had a 95%+ success rate over 30-year periods.

Example: If your FIRE number is $1.5M, you can withdraw $60,000/year ($5,000/month) and your portfolio is expected to last 30+ years. Many in the FIRE community use a more conservative 3.5% rate for extra safety.

NetWorthCast uses 4% by default when calculating your FIRE target, based on your total monthly costs.

Frequently Asked Questions

What is a FIRE number?

Your FIRE number is the total amount you need invested to live off the returns indefinitely. It equals your annual expenses divided by 0.04 (or multiplied by 25). Once your liquid assets reach this number, you're financially independent.

How is the FIRE number calculated?

FIRE number = Annual Expenses ÷ 0.04. This is based on the Trinity Study's 4% safe withdrawal rate. NetWorthCast calculates this automatically from your monthly costs and shows it on the forecast chart.

What is the difference between Lean FIRE, Fat FIRE, and Coast FIRE?

Lean FIRE = frugal independence (<$40k/yr). Fat FIRE = comfortable independence ($100k+/yr). Coast FIRE = enough invested that compound growth alone reaches your FIRE number by traditional retirement age.

When can I retire early?

That depends on your savings rate, investment returns, and expenses. NetWorthCast projects your exact FIRE date using your real financial data — not just estimates.