Runway
How many months a company can operate before it runs out of cash.
Runway is cash on hand divided by net monthly burn. Twelve months of runway means twelve months until the balance reaches zero at the current rate.
Runway should be calculated on today's numbers, not projected ones. Building expected revenue growth into the model is how founders end up with materially less time than they believed.
A raise takes three to six months at seed and longer at Series A. Starting at 12 to 18 months of runway leaves room to negotiate; starting at six means raising under pressure, which investors detect and price in.