Not a dumb question, I've wondered something similar when wondering about making a paracord bracelet..
I ended up doing a test bit, weaving a short length, then undoing it and measuring how much cord I had used, and then multiplying to get the desired total length (if that makes sense). So if a foot of paracord makes 3 inches of bracelet, then I need 4 times as much paracord as the intended length of my bracelet.