The Trinity Study's finding that a retiree can safely withdraw 4% of their starting portfolio each year (adjusted for inflation) and have it last 30+ years with high probability. Your FIRE number is annual expenses × 25 — the inverse of 4%.

Is 4% still safe in 2026?

Debated. Some researchers argue 3-3.5% is safer given lower projected bond yields and higher equity valuations. Others note the original study was conservative. Most FIRE planners target 3.25-3.75% for long retirements (50+ years) and 4% for traditional retirement ages.

What's the difference between lean-FIRE and fat-FIRE?

Lean-FIRE: $30-50k annual spend, typically requires $750k-1.25M invested. Fat-FIRE: $150k+ annual spend, typically $3.75M+. Coast-FIRE: already have enough that compound growth alone will hit your number by retirement age, so you can stop saving.

How do I account for healthcare before Medicare?

The big unknown in US FIRE. ACA marketplace premiums depend on taxable income, not wealth — so keep realized income low in retirement years to qualify for subsidies. Budget $10-25k/year for pre-Medicare healthcare as a planning assumption.

Money & Finance · Free tool

FIRE Number Calculator

Determine financial independence targets based on expenses and SWR for lean, regular, and fat FIRE. Free online calculator with no sign-up.

Updated June 2026

Annual ExpensesSWR %Current AgeCoast AgeExpected Growth %

FIRE Number

$1,250,000

Lean (25x)

$1,250,000

Fat (33x)

$1,650,000

Coast @ 45

$323,024

For guidance only — not financial advice. SWR research assumes a 30-year horizon.

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What it does

Calculate your FIRE number at lean, regular, and fat levels in one view.

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How to use it

Enter annual expenses.
Set SWR.
Read all three FIRE targets.

Frequently asked questions

What's the 4% rule?: The Trinity Study's finding that a retiree can safely withdraw 4% of their starting portfolio each year (adjusted for inflation) and have it last 30+ years with high probability. Your FIRE number is annual expenses × 25 — the inverse of 4%.
Is 4% still safe in 2026?: Debated. Some researchers argue 3-3.5% is safer given lower projected bond yields and higher equity valuations. Others note the original study was conservative. Most FIRE planners target 3.25-3.75% for long retirements (50+ years) and 4% for traditional retirement ages.
What's the difference between lean-FIRE and fat-FIRE?: Lean-FIRE: $30-50k annual spend, typically requires $750k-1.25M invested. Fat-FIRE: $150k+ annual spend, typically $3.75M+. Coast-FIRE: already have enough that compound growth alone will hit your number by retirement age, so you can stop saving.
How do I account for healthcare before Medicare?: The big unknown in US FIRE. ACA marketplace premiums depend on taxable income, not wealth — so keep realized income low in retirement years to qualify for subsidies. Budget $10-25k/year for pre-Medicare healthcare as a planning assumption.

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