What is FIRE and how does it work?

FIRE stands for Financial Independence, Retire Early. The core idea is to aggressively save and invest (often 50–70% of income) to build a portfolio large enough to cover your living expenses indefinitely through investment returns. Once your portfolio reaches roughly 25 times your annual expenses, you are considered financially independent.

What is a FIRE number?

Your FIRE number is the portfolio size at which your investment returns can cover your annual expenses without depleting the principal. It's typically calculated as your annual expenses multiplied by 25 (based on the 4% safe withdrawal rate). For example, if you spend $40,000 per year, your FIRE number would be $1,000,000.

What is the difference between lean FIRE, regular FIRE, and fat FIRE?

Lean FIRE means reaching financial independence on a minimal budget (typically under $40,000/year in expenses). Regular FIRE targets a comfortable middle-class lifestyle. Fat FIRE aims for a more affluent retirement with annual spending of $100,000 or more. The core math is the same — the difference is the expense level you're targeting and therefore the portfolio size needed.

Retirement

What Is Your FIRE Number?

Calculate your path to Financial Independence and Retire Early. Discover your FI number, see how long until you can retire, and explore every FIRE milestone — from Coast FI and Lean FIRE to Barista FIRE and Fat FIRE.

Current Monthly Payment

—

New Monthly Payment

—

Est. Interest Saved

—

Break-Even

—

Current Age

Annual Expenses

Current Savings / Net Worth

Monthly Savings

Expected Annual Return

FIRE Number (expenses × 25): $1,250,000 — based on the 4% rule

Estimated FIRE Age

15y 7m from now

Years to FIRE

15y 7m

FIRE Number

$1,250,000

Portfolio at FIRE

$1,390,129

Monthly Savings$3,000

Annual Savings$36,000

Portfolio Growth Toward FIRE

Projected portfolio balance by age based on current savings rate and expected return.

Income & Expenses

Your Savings Rate

33%

Strong progress

Annual Gross Income

Effective Tax Rate

After-tax: $75,000

Annual Expenses

Monthly: $4,167

Monthly Income (after tax):$6,250

Monthly Expenses:-$4,167

Monthly Savings:$2,083

Current Position

Current Invested Savings

Current Age

Assumptions

Pre-FI Return

Post-FI Return

Withdrawal Rate

Inflation

Your FI Number

$1,250,000

$50,000 ÷ 4% SWR

Barista FIRE (Optional)

Barista FI means your portfolio covers expenses minus part-time income. Enter an expected annual side income to calculate this milestone.

Annual Part-Time Income

Barista FI Number: $1,250,000

Estimated Years to Financial Independence

18y 7m

Estimated FI at age 49 (year 2045)

Progress

Coast FI

6 months

Lean FI

11y 4m

Savings Rate

33%

Fat FI

23y 5m

FIRE Projection

Projected portfolio balance and annual savings over time.

FIRE Milestones

Coast FI

Can stop saving; investments will grow to FI by age 65

$117,079

6 months · Age 31

Lean FI

Can cover basic expenses (50% of current spending)

$625,000

11y 4m · Age 41

Financial Independence

Can cover full expenses indefinitely

$1,250,000

18y 7m · Age 49

Fat FI

Can cover 150% of current expenses

$1,875,000

23y 5m · Age 53

The Math of FIRE

The 4% Rule: Withdrawing 4% of a portfolio annually has historically supported a 30+ year retirement horizon.

FI Number: $50,000 ÷ 4% = $1,250,000

Savings Rate Impact: A 50% savings rate typically corresponds to approximately 17 years to FI; 75% corresponds to approximately 7 years.

About This Analysis

This calculator provides estimates based on the inputs you supply. It assumes standard amortization and does not account for taxes, insurance, PMI, prepayment penalties, or the opportunity cost of funds. Results are for informational and educational purposes only and should not be considered financial advice. Consult a qualified professional before making financial decisions.

·Assumes constant real returns and a fixed savings rate over the projection period.
·Does not account for Social Security, pensions, or changes in spending patterns.
·The 4% rule is a historical guideline, not a guarantee of portfolio longevity.

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