Calculate Your FIRE Number with ETFs

Last updated: March 2026

Audience Profile

Age Range

25-40

Situation

Wants to know exactly how much is needed to achieve financial independence

Main Concern

Understanding the target portfolio size and timeline for early retirement

Your FIRE number is the total invested amount needed to sustain your lifestyle indefinitely. It depends on your annual spending, withdrawal rate, and expected returns. Understanding this number transforms early retirement from a dream into a concrete, trackable goal.

How to Calculate Your FIRE Number

The basic FIRE number formula is simple: Annual Expenses multiplied by 25. This assumes a 4% withdrawal rate, meaning you withdraw 4% of your portfolio each year to fund your expenses. If you spend $50,000 per year, your FIRE number is $1,250,000. If you spend $80,000, it is $2,000,000.

For early retirees facing 40-60 year retirements, many prefer a more conservative multiplier of 28-33, corresponding to withdrawal rates of 3.0-3.5%. At a 3.5% rate, $50,000 in annual spending requires $1,428,571. The extra cushion provides significantly more protection against sequence of returns risk.

Your FIRE number is driven entirely by spending, not income. A doctor earning $300,000 who spends $120,000 needs $3,000,000 at the 4% rule, while a teacher earning $60,000 who spends $30,000 needs only $750,000. This is why reducing expenses has a double benefit for FIRE: it lowers your target number and increases your savings rate simultaneously.

Savings Rate and Time to FIRE

Your savings rate is the most powerful variable in the FIRE equation. It determines your timeline more than income, returns, or any other factor. At a 10% savings rate, it takes roughly 51 years to reach FIRE. At 30%, it takes about 28 years. At 50%, about 17 years. At 70%, roughly 8.5 years.

The relationship is nonlinear because a higher savings rate simultaneously increases the amount you invest and decreases the amount you need. Someone saving 50% is investing half their income while only needing to replace the other half. This double effect is what makes high savings rates so powerful.

Track your savings rate monthly. Calculate it as total savings and investments divided by total take-home pay. Include 401(k) contributions, IRA contributions, taxable investments, and extra debt payments above minimums. Aim to increase your savings rate by 1-2 percentage points every quarter until you reach your target.

Tracking Progress Toward Your Number

Breaking your FIRE number into milestones makes the journey manageable. Your first $100,000 is the hardest because investment returns contribute relatively little. From zero to $100,000 might take 3-5 years, but $100,000 to $200,000 often takes only 2-3 years as returns accelerate your progress.

Each subsequent $100,000 milestone comes faster. At 7% returns with no additional contributions, $500,000 doubles to $1,000,000 in about 10 years. But with continued contributions, it happens much faster. This accelerating momentum is what keeps FIRE seekers motivated through the middle years.

Use a simple spreadsheet or net worth tracking app to monitor your progress monthly. Plot your net worth against your projected trajectory assuming your target savings rate and a conservative 6-7% real return. Seeing your actual results track your projections, or outpace them during bull markets, provides powerful motivation to stay the course.

Suggested Portfolio Allocation

Projected Growth of $10,000

Recommended ETFs

VTI

Core U.S. holding with lowest costs for maximizing long-term compounding toward your FIRE number

VXUS

International equity exposure ensuring global diversification as your portfolio grows

VNQ

REIT exposure for real estate diversification and inflation protection over the accumulation phase

Action Steps

Calculate Your Annual Spending

Track every expense for 3 months to establish your true annual spending. Include rent or mortgage, food, transportation, healthcare, insurance, entertainment, and miscellaneous costs. Be honest because underestimating leads to a FIRE number that is too low.

Determine Your FIRE Number

Multiply your annual spending by 25 for a standard FIRE number, or by 30 for a conservative number. Write this target down and post it somewhere visible. This is the number that represents your financial freedom.

Calculate Your Savings Rate and Timeline

Divide your monthly savings by your monthly take-home pay to find your savings rate. Use a FIRE calculator to determine how many years until you reach your number at your current rate. Identify opportunities to increase your savings rate by even 5% to shorten the timeline.

Frequently Asked Questions

Does my FIRE number include my house?

Your primary residence should not be counted toward your FIRE number because it does not generate withdrawable income. Your FIRE number represents investable assets in brokerage accounts, IRAs, and 401(k)s. However, paying off your mortgage before FIRE reduces your annual expenses, which in turn reduces the FIRE number you need. A paid-off house is valuable but as an expense reducer, not a portfolio asset.

Should I use the 4% rule or something more conservative?

For retirements under 30 years, the 4% rule works well. For FIRE retirees expecting 40-60 year retirements, use 3.25-3.5% for safety. If you plan to have any side income, Social Security, or spending flexibility, 3.75-4% can work. Run your numbers at multiple withdrawal rates to understand the range of portfolio sizes that could work for your situation.

How do I account for future Social Security in my FIRE number?

Social Security acts as a future income stream that reduces the amount your portfolio needs to provide. If you expect $20,000 per year from Social Security starting at age 62, your portfolio only needs to cover expenses minus $20,000 from that age forward. Some FIRE planners reduce their target by 5-10% to account for Social Security, while others treat it as a bonus safety margin.

Ready to start investing in ETFs? We use and recommend Interactive Brokers (IBKR) for its low fees, global market access, and professional-grade tools. New accounts can earn free IBKR stock depending on your deposit amount.

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