Beginner guide
This starts with monthly cash flow
FIRE is not only a big target number. The first question is whether money is left over each month after spending and debt payments.
The calculator uses salary plus side income minus spending to estimate monthly savings. Then it models debt and investment growth month by month.
- If monthly savings are negative, the FIRE date cannot be realistic yet.
- Debt principal raises the target because it still has to be dealt with.
- As debt is paid down, the target line can move lower.
Use this as a direction check, not a promise
A FIRE estimate depends on return rate, spending, income, debt interest, and the target asset amount. Any of those can change.
The useful part is the crossover: the point where projected assets meet the target after debt is considered.
Formula
Monthly savings = salary + side income - spending. Monthly debt interest is calculated from loan principal and annual loan rate. FIRE target = desired retirement assets + remaining loan principal.
Example
If the desired retirement asset target is $1,000,000 and debt falls from $500,000 over time, the FIRE target line moves down as the loan is repaid.
Result notes
- Results are estimates based on the values you enter.
- Calculators with schedules show how values change over time.
- For financial, health, or construction decisions, compare these estimates with professional advice when needed.
Frequently asked questions
How is this different from a retirement calculator?
A retirement calculator projects savings at a chosen age. This FIRE calculator finds when invested assets cross the target after loan repayment is modeled.
Why include loan principal?
Remaining debt is added to the FIRE target, then gradually falls as monthly payments reduce the loan balance.
Is this guaranteed?
No. It is a planning estimate. Investment returns, spending, income, taxes, and debt terms can change.