Quick guide
How to use this calculator
- Enter one scenario using a consistent currency and the periods shown by each label.
- Keep targets, coverage time, income basis, and expected return aligned with your own planning definition.
- Read the result with the visible assumptions before using it in a financial decision.
Calculation method
Calculation method
Usable cash = available cash − immediate committed costs; monthly burn = recurring expenses − recurring income; runway = usable cash ÷ positive monthly burn.
Exact decimal/rational arithmetic is used for cash-flow totals. The savings-goal projection uses stable logarithmic compounding with a zero-rate limit and rejects overflow or a nonzero result that would become zero. Repeating ratios use parentheses; an ellipsis marks a preview longer than 12 decimal places.
Worked example
Worked example
After 2,000 of immediate costs, 20,000 of cash leaves 18,000; expenses of 4,000 and income of 1,000 create a 3,000 burn and a 6-month runway.
Usable cash = available cash − immediate committed costs; monthly burn = recurring expenses − recurring income; runway = usable cash ÷ positive monthly burn.
Supported inputs
Precision and limits
Visible input limits
Amounts accept up to 30 digits and 12 decimal places and are capped at 1e12. Rates are capped at 1000%; whole-month horizons are capped at 1,200, with 120 months for reserve coverage and sabbatical duration.
International scope
No currency, country, benefit system, recommended fund size, guaranteed return, or savings-rate standard is assumed.
Planning boundary
Results are deterministic projections of entered assumptions, not guarantees, investment advice, or a judgment about an adequate reserve.
Calculator-specific assumptions
A non-positive entered burn is reported as no finite depletion under the scenario, not as unlimited financial security. Irregular cash flows, investment volatility, inaccessible assets, and inflation are excluded.