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

Already invested ($)

Annual saving ($)

Lean annual spending (today's $)

Withdrawal rate (%)

Real return (%)

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

Same identity as every other FIRE number: spending divided by the withdrawal rate. The years figure inverts the ordinary-annuity future value, so a $200,000 start plus $20,000 a year at 5% real reaches a $1,000,000 lean number in a little over 17 years. The Fat FIRE calculator is the other end of the same scale.

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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