What Is My FIRE Number? How to Calculate Early Retirement
FIRE stands for Financial Independence, Retire Early. The concept is simple: save aggressively, invest wisely, and build a portfolio large enough that you can live off the investment returns without needing a paycheck. The number you need to reach is your "FIRE number," and the math behind it is surprisingly straightforward.
Calculate Your FIRE Number
Enter your expenses, savings, and expected returns to see your timeline.
Use the FIRE CalculatorThe 25x Rule: The Foundation of FIRE
Your FIRE number is 25 times your annual expenses. That is it. If you spend $40,000 per year, your FIRE number is $1,000,000. If you spend $60,000 per year, you need $1,500,000. If you can live on $30,000, you only need $750,000.
The 25x rule is the inverse of the 4% rule, which comes from the Trinity Study. The study found that a portfolio of stocks and bonds can sustain a 4% annual withdrawal rate (adjusted for inflation each year) for at least 30 years with a high probability of success. Since 1 / 0.04 = 25, you need 25 times your annual spending to safely withdraw 4% per year.
Your Savings Rate Is Everything
In the FIRE community, your savings rate matters far more than your income. A person earning $200,000 who spends $180,000 (10% savings rate) will take far longer to reach FIRE than someone earning $80,000 who spends $40,000 (50% savings rate). Higher savings rates work a double magic: you save more money each year and you need less money in total because your expenses are lower.
| Savings Rate | Years to FIRE | Key Insight |
|---|---|---|
| 10% | 51 years | Standard retirement timeline |
| 25% | 32 years | Retire a few years early |
| 50% | 17 years | The sweet spot for most FIRE seekers |
| 65% | 10.5 years | Aggressive but achievable for high earners |
| 75% | 7 years | Extreme frugality or very high income |
These numbers assume a 5% real (after-inflation) return on investments and starting from zero savings. Your actual timeline will differ based on your starting balance and investment returns.
The Types of FIRE
Traditional FIRE
The standard version: accumulate 25x your current annual expenses. You are fully financially independent and never need to work again. Most people target somewhere between $750,000 and $2,000,000 depending on their lifestyle and location.
Lean FIRE
Lean FIRE means reaching financial independence on a very lean budget, typically under $40,000 per year in expenses (or under $25,000 for an individual). This means a FIRE number below $1,000,000. It is more achievable but requires maintaining a frugal lifestyle indefinitely. People who pursue Lean FIRE often live in low-cost-of-living areas, and some move abroad to stretch their dollars further.
Fat FIRE
Fat FIRE is the opposite: financial independence with a generous lifestyle, typically $100,000 or more per year in expenses. This requires $2,500,000 or more saved. Fat FIRE is common among high-income professionals (doctors, lawyers, tech workers) who want to retire early without downsizing their lifestyle.
Barista FIRE
Barista FIRE means you have saved enough that your portfolio covers most of your expenses, but you still work a low-stress part-time job to cover the gap and maintain health insurance. The name comes from the idea of working at a coffee shop (Starbucks famously offers health insurance to part-time employees). This is an attractive middle ground for people who want to leave their career but are not quite at full financial independence.
Coast FIRE
Coast FIRE means you have saved enough that compound growth alone will carry your portfolio to full FIRE by traditional retirement age (60-65), even if you never invest another dollar. Once you hit your Coast FIRE number, you only need to earn enough to cover current living expenses. No more saving required. This is a powerful psychological milestone because it eliminates the stress of "falling behind" on retirement savings.
Example: Coast FIRE at age 30
If you have $200,000 invested at age 30 and expect a 7% real return, that money will grow to roughly $1,500,000 by age 60 without adding a single dollar. If your expected retirement spending is $60,000 per year ($1,500,000 / 25), you have already hit Coast FIRE.
How Compound Interest Powers FIRE
The FIRE math works because of compound returns. In the early years, your contributions do most of the work. But as your portfolio grows, the investment returns take over. A $500,000 portfolio earning 7% generates $35,000 in returns in a single year. At $1,000,000, that is $70,000. Eventually, your money makes more money in a year than you can save from your salary.
This is why starting early is so powerful, and why the Compound Interest Calculator is such a useful tool for FIRE planning. Even small contributions in your 20s have decades to compound.
Where to Put Your FIRE Money
The most common FIRE investment strategy is simple: low-cost index funds. A total U.S. stock market index fund (like VTSAX or VTI) combined with an international index fund gives you broad diversification at minimal cost. Many FIRE adherents follow a "three-fund portfolio" of U.S. stocks, international stocks, and bonds.
Tax-advantaged accounts should be maximized first: 401(k) (up to $23,500 in 2025, or $31,000 if over 50), Roth IRA ($7,000, or $8,000 if over 50), and HSA ($4,300 individual, $8,550 family in 2025). After maxing these, invest in a taxable brokerage account. The Retirement Calculator can help you project growth across these accounts.
Common FIRE Mistakes
Ignoring healthcare costs. In the U.S., health insurance outside an employer plan is expensive. ACA marketplace plans can cost $300-800+ per month depending on your age and location. Budget for this before declaring yourself financially independent.
Using overly aggressive return assumptions. Planning around 10% returns with no inflation adjustment is dangerous. Use 5-7% real (after-inflation) returns for conservative projections.
Neglecting taxes on withdrawals. Money in a traditional 401(k) or IRA will be taxed as ordinary income when you withdraw it. A Roth conversion ladder or other tax-efficient withdrawal strategy is important for early retirees.
Not accounting for lifestyle changes. Your spending at 35 may be very different from your spending at 55. Children, health care, travel, and housing costs can shift significantly.
Run Your FIRE Scenario
See how savings rate, return assumptions, and expenses affect your FIRE timeline.
Use the FIRE CalculatorFIRE FAQ
Related Tools
Calculate your FIRE timeline with the FIRE Calculator. See how contributions grow over time with the Compound Interest Calculator. Plan for traditional retirement with the Retirement Calculator. Set and track a target with the Savings Goal Calculator. Calculate your take-home pay in any state with the Paycheck Calculator.