1. Enter current cash
Use unrestricted cash available to fund operations.
2. Enter monthly net burn
Subtract recurring cash inflows from cash outflows for a representative month.
3. Set a minimum reserve
Enter the balance you do not want runway to consume.
4. Review runway months
The result divides usable cash by monthly burn.
5. Use the end date as a planning marker
Treat it as an estimate and begin financing planning well before the modeled date.
Where:
Assumptions: Burn remains constant, cash is available, and no financing or extraordinary cash event occurs. The end date converts months using an average month length.
Estimated cash runway above reserve.
Use the result as a planning estimate based on the assumptions above.
Given: A startup has $2,100,000 in cash, burns $175,000 per month, and wants to preserve a $350,000 reserve.
Calculation: Usable cash: $2,100,000 − $350,000 = $1,750,000. Runway: $1,750,000 ÷ $175,000 = 10 months.
Result: The company has about 10 months of runway before reaching the selected reserve.
No. Use only cash that can legally and operationally fund the modeled expenses.
The calculator shows unlimited runway because current operations are not consuming net cash under that input.
Use a detailed monthly cash forecast or test several burn scenarios instead of relying on one average.
A reserve can represent payroll protection, debt covenants, or a board-set liquidity floor.
Runway measures time supported by existing cash; funding need estimates the cash required to cover a target period.