What is the FIRE number and how is it calculated?

The FIRE number is the portfolio size needed to sustain your retirement spending indefinitely. It equals your annual expenses divided by your safe withdrawal rate (e.g., annual expenses / 0.04 for a 4% SWR).

How does the savings rate affect years to retirement?

Savings rate is the single biggest lever in FIRE planning. A 50% savings rate typically leads to retirement in roughly 17 years from zero; a 75% rate cuts that to about 7 years, regardless of income level.

Should I include Social Security benefits in my FIRE projections?

Early retirees often exclude or heavily discount Social Security because claiming before 62 is not possible and benefit rules may change. If you do include it, model it as a conservative partial offset beginning at your projected claim age.

Early Retirement (FIRE) Calculator

Find out how many years until you can retire early using the FIRE (Financial Independence, Retire Early) framework. Calculate your FIRE number, years to retirement, and whether you are on track based on current savings and contributions.

By AbraCalc Editorial Team · Reviewed by AbraCalc Methodology Review · Last reviewed: 2026-06-25

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How to use this tool

Enter current retirement savings, annual contributions, expected annual expenses in retirement, expected annual investment return and safe withdrawal rate in the fields above.
Results update instantly as you type — or click Calculate.
Read your years to early retirement and the full breakdown beneath it.

⚠ This tool provides general estimates for education only and is not financial, tax or legal advice. Figures may not reflect your situation — verify with a qualified professional.

Formula

FIRE Number: Target = Annual Expenses / Safe Withdrawal Rate

Portfolio growth each year: Portfolio_n+1 = Portfolio_n × (1 + r) + Annual Contributions

Retirement is reached when Portfolio ≥ FIRE Number.

How it works

The FIRE number is the total portfolio size needed to sustain your retirement spending indefinitely, derived by dividing annual expenses by the safe withdrawal rate (typically 4%, based on the Trinity Study). Starting from current savings, the calculator compounds the portfolio at the expected return each year and adds annual contributions until the portfolio reaches the FIRE number. The result is the number of years until financial independence.

Worked example

FIRE with $500K Saved and No Additional Contributions at 7% Return

Annual expenses = $40,000; safe withdrawal rate = 4%; FIRE number = $40,000 / 0.04 = $1,000,000.
Current savings = $500,000; annual contributions = $0; return = 7%.
Year 1 portfolio = $500,000 × 1.07 = $535,000.
Portfolio compounds at 7% annually until it reaches $1,000,000.

FIRE number is $1,000,000. With $500,000 at 7% growth and no contributions, retirement is reached in approximately 10.2 years.

Common mistakes to avoid

Using a 4% safe withdrawal rate without adjusting for a retirement horizon longer than 30 years — retiring at 40 means a 50+ year drawdown, where research suggests 3.0-3.5% is safer.
Forgetting to account for healthcare costs before Medicare eligibility at 65, which can add thousands of dollars annually to early-retirement expenses.
Underestimating real investment returns by not subtracting inflation — a nominal 7% return with 3% inflation is only 4% real growth, significantly extending the years to FIRE.

Key terms

What is the FIRE number?: The total portfolio value needed to retire, calculated as annual expenses divided by the safe withdrawal rate. At 4% SWR, the FIRE number is 25 times annual spending.
What is the safe withdrawal rate?: The percentage of a portfolio that can be withdrawn annually without depleting the portfolio over a 30+ year retirement. The 4% rule comes from the Trinity Study (1998).
What is FIRE?: Financial Independence, Retire Early — a movement focused on aggressive saving and investing to reach financial independence well before traditional retirement age.
Does the calculator account for inflation?: Use a real (inflation-adjusted) investment return (e.g., 7% nominal minus ~3% inflation = 4% real) and express expenses in today's dollars for inflation-adjusted results.

Frequently asked questions

What is the FIRE number and how is it calculated?: The FIRE number is the portfolio size needed to sustain your retirement spending indefinitely. It equals your annual expenses divided by your safe withdrawal rate (e.g., annual expenses / 0.04 for a 4% SWR).
How does the savings rate affect years to retirement?: Savings rate is the single biggest lever in FIRE planning. A 50% savings rate typically leads to retirement in roughly 17 years from zero; a 75% rate cuts that to about 7 years, regardless of income level.
Should I include Social Security benefits in my FIRE projections?: Early retirees often exclude or heavily discount Social Security because claiming before 62 is not possible and benefit rules may change. If you do include it, model it as a conservative partial offset beginning at your projected claim age.