How to use it
- Enter the cash you have now and your average monthly expenses.
- Enter monthly revenue and, if it is growing, the monthly growth rate.
- Pick the starting date, today by default. The runway and the zero-cash date update as you type.
How it works
- Month k: revenue = revenue × (1 + growth)^(k − 1); net burn = expenses − that revenue.
- Each month’s net burn is taken from the cash. In the month the cash would go below zero, the runway ends part-way: (k − 1) + cash left ÷ that month’s net burn.
- If revenue reaches expenses while there is still cash (with flat or rising revenue), the company no longer burns cash and there is no zero-cash date.
- Zero-cash date = start + runway × 30.44 days.
Worked example
Cash 500,000, expenses 60,000 a month, revenue 20,000 a month, no growth. Net burn is 40,000, so the runway is 500,000 ÷ 40,000 = 12.5 months. Starting on 3 November 2026, the cash runs out around 18 November 2027.
With cash of 100,000, expenses of 30,000 and revenue of 10,000 growing 10% a month, the net burn falls from 20,000 to 15,359 in month 5, leaving 11,051. Month 6 burns 13,894.90, so the runway is 5 + 11,051 ÷ 13,894.90 ≈ 5.8 months.
Tips
- Use average expenses over the last few months, not one unusual month.
- Fundraising takes months. Many founders start well before the cash runs low.
- Growth assumptions matter a lot: compare a cautious and an optimistic case.