What is a FIRE number?

Your FIRE number is the portfolio size needed to sustain your annual expenses indefinitely using a safe withdrawal rate. It is calculated as your annual expenses divided by your safe withdrawal rate (e.g., $50,000 / 0.04 = $1,250,000).

The 4% rule is a guideline from the Trinity Study suggesting that retirees can withdraw 4% of their portfolio in the first year of retirement, then adjust for inflation each year, with a very high probability of not running out of money over a 30-year retirement.

How does savings rate affect my FIRE timeline?

Savings rate is the single most powerful lever for reaching FIRE. A higher savings rate both increases the money invested each year and decreases the annual expenses you need to cover, lowering your FIRE number. Someone saving 50% of income can typically retire in about 17 years, while saving 70% can retire in roughly 8 years.

Should I include Social Security in my FIRE plan?

Including Social Security reduces the portfolio needed at retirement because part of your expenses will be covered by SS benefits. However, many FIRE planners treat it as a bonus rather than relying on it, since benefits could change and early retirees may have decades before they can collect.

FIRE Calculator — When Can You Retire? — Abel's Financial Calculators

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FIRE Number

—

target portfolio (today's dollars)

Monthly Savings

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invested per month

Withdrawal Success

—

portfolio survives to 90

FIRE Snapshot

FIRE Number

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in today's dollars

Monthly Savings

—

invested per month

Years to FIRE

—

median

FIRE Age

—

median

Withdrawal Success

—

portfolio survives to 90

Portfolio at FIRE

—

median, future dollars

Portfolio Growth Projection (Monte Carlo)

All values in future (nominal) dollars. The FIRE target line grows with inflation over time.

Median (50th)

25th–75th

10th–90th

FIRE Target

Chart shows Monte Carlo simulation of portfolio growth from your current age to age 90. Each simulation year randomly samples a historical year (1926–2024) and uses the actual asset class returns and CPI from that year. Shaded bands represent the range of outcomes. The red dashed line is your FIRE target. The green dashed line marks the median FIRE age.

Savings Amount Sensitivity

How much do you need to save to retire at a given age? Each row uses Monte Carlo simulation (200 runs) to estimate the annual savings needed.

Target FIRE Age	Years to FIRE	Annual Savings Needed	Monthly

Year-by-Year Breakdown

Age	Expenses	Annual Savings	Portfolio (Median)	Portfolio (10th)	Portfolio (90th)	FIRE Prob.