Cash Runway Calculator
Cash runway is the number of months your business can keep operating before it runs out of cash at its current net burn rate. It is the single most important survival metric for any startup. Enter your current cash balance and your average monthly net burn (or your monthly revenue and expenses) to see your runway in months and your projected zero-cash date.
Cash runway formula
Monthly net burn = monthly expenses - monthly revenue
Runway (months) = cash balance / monthly net burn
Runway (days) = runway months * 30.44
If revenue exceeds expenses, net burn is negative (cash-flow positive) and runway is effectively unlimited at the current rate. The calculator flags this case.
Worked example
A startup holds 1,200,000 dollars in cash, spends 180,000 dollars per month, and earns 80,000 dollars per month. Net burn = 180,000 - 80,000 = 100,000 dollars per month. Runway = 1,200,000 / 100,000 = 12.00 months, or about 365 days. The company should plan its next raise well before this date.
Notes on runway
- A common guideline is to raise a new round when 6 to 9 months of runway remain, since fundraising takes time.
- Net burn uses cash actually leaving the business, which can differ from accounting expenses (for example, prepaid annual contracts).
- If you are cash-flow positive (revenue above expenses), runway is unlimited at the current rate and this tool reports that.
- Recalculate whenever hiring, pricing, or spending changes materially.
Cash Runway Calculator: frequently asked questions
How do I calculate cash runway?
Divide your current cash balance by your monthly net burn rate. Net burn is monthly expenses minus monthly revenue. For example, 1,200,000 dollars of cash divided by 100,000 dollars net burn equals 12 months of runway.
What is a healthy cash runway?
Many investors suggest keeping at least 12 to 18 months of runway, and starting a new fundraise when roughly 6 to 9 months remain because raising capital takes time. The right level depends on your stage and growth plans.
What is the difference between gross burn and net burn?
Gross burn is total cash spent each month. Net burn subtracts incoming revenue, so it is gross burn minus revenue. Runway is based on net burn because revenue offsets some spending.
What happens if I am cash-flow positive?
If your monthly revenue exceeds your monthly expenses, your net burn is negative and you are adding cash rather than depleting it. In that case runway is effectively unlimited at the current rate, which this calculator indicates.
Sources and methodology
- Cash runway is defined arithmetically as cash balance divided by net monthly burn; no external figure is hardcoded.
- U.S. Small Business Administration: Manage your finances.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.