About the Startup Runway Calculator
The Startup Runway Calculator tells you how many months of operating cash remain before your bank balance hits zero, based on your current cash on hand and your net monthly burn rate. It turns the founder question of how much time is left into a specific number of months and an estimated zero-cash date.
How It Works
You enter your current cash balance and your net monthly burn rate, defined as monthly expenses minus monthly revenue. The calculator divides cash balance by monthly burn to get months remaining, then adds that many whole months to today's date to estimate the calendar month you would run out of cash. If net burn is zero or negative, meaning revenue covers or exceeds expenses, the calculator reports the business as cash-flow positive with effectively unlimited runway at the current rate.
Formula & Methodology
To estimate by hand, divide current cash balance by net monthly burn. For example, $500,000 divided by $45,000 equals roughly 11.1 months of runway. To estimate the zero-cash date, round the months down to a whole number and count forward that many months from today's date.
Examples
A seed-stage startup mid burn
With $500,000 in the bank and a net monthly burn of $45,000, runway comes to 11.1 months, putting the estimated zero-cash date about eleven months from today.
A leaner, bootstrapped team
A startup with $120,000 in cash and a net monthly burn of $8,000 has 15.0 months of runway, giving the team over a year to hit milestones before needing to raise again or cut costs further.
Advantages
- Turns two figures already tracked in any startup's bank statement into a single, easy-to-communicate number for the team and board.
- Produces an estimated zero-cash month, useful for backward-planning a fundraising timeline.
- Automatically flags cash-flow-positive businesses instead of returning a confusing negative or undefined runway figure.
Common Mistakes
- Using gross monthly expenses instead of net burn (expenses minus revenue), which understates runway for a business with meaningful revenue.
- Treating the calculated runway as fixed when burn typically changes month to month as headcount, marketing spend, or revenue shifts.
- Waiting until runway is critically short to start fundraising, when the zero-cash date should ideally trigger action several months in advance given how long raises typically take.
Edge Cases to Watch For
- If net monthly burn is zero or negative, there is no runway to calculate; the calculator instead flags the business as cash-flow positive, since dividing by a non-positive burn rate produces a meaningless result.
- The zero-cash date is estimated by adding the rounded-down number of months to today's date, so it reflects a month and year, not a precise day.
- The calculation assumes burn stays constant going forward; it does not account for planned hiring, a funding round, or seasonal revenue swings that would change the monthly figure.
- Net burn nets revenue against expenses into a single figure, so two businesses with very different gross spending can show the same runway if their net cash outflow matches.
Common Use Cases
- Founders tracking how many months of operation remain before the next fundraise is required.
- Startup finance teams building board updates that need a current, defensible runway figure.
- Investors and advisors quickly sanity-checking a startup's cash position during diligence conversations.