Runway calculator

Runway is the number of months left before you run out of cash, at your current spending rate. It's one of the metrics that causes founders the most anxiety — for good reason: it sets a concrete deadline.

The calculation starts with net monthly burn: monthly expenses minus monthly revenue. If revenue exceeds expenses, your net burn is negative — you're profitable, and the concept of runway no longer strictly applies.

When net burn is positive, runway in months is simply cash on hand divided by net monthly burn. Worked example: you have $120,000 in the bank, $18,000 in monthly expenses, and $9,000 in revenue. Net burn is $9,000/month. Runway is 120,000 / 9,000 ≈ 13.3 months — a comfortable zone, but worth watching if expenses rise.

The estimated cash-out date simply adds that many months to today's date. It's a theoretical date, not a prophecy: it assumes expenses and revenue stay constant, which is almost never true in practice.

Two common mistakes. The first: calculating net burn off a single unusual month — a large one-off payment or an unusual cash inflow skews the calculation. Better to average over a 3-to-6-month rolling window. The second: ignoring the burn trajectory. A 13-month runway based on today's expenses means much less if you're planning to hire three people next month — runway should be recalculated after every significant hiring or spending decision.

When the metric stops meaning much: for an already-profitable company, runway in the strict sense no longer applies. Runway is also misleading right after a fundraise: cash on hand is temporarily high, but expenses often rise in parallel, shrinking real runway faster than expected if you don't recalculate regularly.