Lean FIRE calculator

The portfolio and years of saving needed to fund a modest retirement — typically around $40,000 a year in today's dollars.

The calculator

Lean FIRE number$1,000,00025× annual spending
Years of saving17.4 yearsWith the contribution above

$40,000 a year at 4.0% is $1,000,000. From $200,000 plus $20,000 a year at 5.0% real, that is 17.4 years.

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How it works

Lean FIRE at this page's $40,000 default is a $1,000,000 nest egg at 4%. From $200,000 invested plus $20,000 a year at 5% real, that is a little over 17 years of saving. Fat FIRE is the same identity at a larger spend — $150,000 a year is $3,750,000, not a different formula.

Same identity as every other FIRE number: spending divided by the withdrawal rate. The years figure inverts the ordinary-annuity future value. The Fat FIRE calculator is the other end of the same scale. Coast and Barista are the milestones on the way: Coast FIRE calculator, Barista FIRE calculator. The generic identity is the FIRE calculator.

Assumptions

Contributions at year end, one real return, no fees, no taxes. The default spending figure is a reference point, not a recommendation.

Frequently asked questions

What is Lean FIRE?
Financial independence at a modest spending level. The number is still spending divided by a withdrawal rate; the spending is just lower, often around $40,000 a year in today’s dollars.
Is $40,000 the official Lean FIRE number?
No. It is a common reference point, not a rule. Use the spending you would actually live on.
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