Lean FIRE calculator
Lean FIRE is financial independence built around a lower-spending lifestyle. There is no single spending ceiling that defines it for every person or household.
This calculator starts with your budget, not someone else’s definition of frugal living. The estimate is educational. This is not financial advice.
Build a budget that can survive an ordinary year
Enter the annual amount your portfolio needs to fund. Include essentials, healthcare, taxes and room for expenses that do not arrive every month. Replacing an appliance or making a necessary trip can matter a great deal in a tight budget.
Keep a current expense separate from an assumption about retirement. A housing payment that might disappear later should not be removed until the timing and replacement costs are understood.
If other income will cover part of the budget, avoid counting it for years before it begins. This simple target calculator does not model changing income phases.
Turn spending into an illustrative target
Portfolio target = annual portfolio-funded spending ÷ initial annual withdrawal rate
Enter your own annual portfolio-funded spending and withdrawal assumption above. The tool shows the arithmetic target for those inputs only; it does not suggest a budget.
A lower budget reduces the calculated target, but it does not remove the risk of investment losses or expenses rising faster than expected.
Test the room left in your budget
Compare your base spending with a higher amount. Ask what you could realistically reduce if income or investment values fell. A budget already cut to necessities may offer less flexibility than its low target suggests.
The withdrawal assumption and investment return are different inputs. A portfolio expected to grow at a certain rate is not automatically able to fund withdrawals at that same rate for your whole retirement.
If the question is how much to invest now and leave untouched until a later retirement, use the Coast FIRE calculator with this spending goal.
Keep the label in perspective
Does Lean FIRE mean never spending on enjoyment?
No. Decide what belongs in your own plan and include it honestly.
Is a low target automatically easier to maintain?
Not if the underlying budget leaves out essential or irregular costs. A useful estimate reflects spending you could actually live with.
Compare the broader FIRE number guide for a closer look at what a withdrawal-based target does and does not show.
Model and transparency
Last updated: 6 November 2026. Deterministic annual calculations, not a historical success test. This is not financial advice.
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