Runway
How many months the cash on hand lasts at the current net burn. Net burn is monthly spend minus monthly revenue.
Real Growth and CashTerm 58 / 81
Formula
Runway (months) = Cash on hand ÷ Monthly net burn
In practice
Burn does not stay fixed: hiring pushes it up and revenue growth pulls it down. The real question is not how many months are left but whether you reach profit before the money runs out. Paul Graham's default alive question assumes expenses stay flat and revenue growth continues at its recent pace. Dividing cash by gross burn is the more conservative calculation: it ignores revenue, so it shows a shorter runway. Say plainly which one you use.