What this tool does
Estimate a FIRE target from annual expenses and a chosen withdrawal rate, then model the time needed to reach it.
How to use it
- Enter annual expenses and a planning withdrawal rate.
- Enter current invested assets, monthly contributions and an assumed annual return.
- Calculate and stress-test lower returns, higher expenses and a lower withdrawal rate.
Formula and method
Target = annual expenses÷withdrawal-rate decimal. Assets then grow monthly at annual return÷12, with the contribution added at month-end, until the target is reached or 1,440 months pass.
Worked example
$40,000 expenses at 4% gives a $1,000,000 target. Starting at $200,000, adding $2,000 monthly and assuming 5% produces a modelled path of roughly 150–250 months.
Common uses
- Comparing savings rates
- Seeing how expenses change the target
- Building conservative and optimistic planning ranges
Limitations
A withdrawal rate is a planning convention, not a promise that money will last. The model covers accumulation only and omits tax, inflation, fees, benefit income, asset allocation, return sequence and changing spending. Seek qualified advice before relying on a FIRE date.
FAQ
Is 4% always safe?
No. Sustainability depends on horizon, portfolio, inflation, fees, taxes, market sequence and flexible spending.
Does this simulate withdrawals after FIRE?
No. It only estimates the target and accumulation time under constant assumptions.