A neighbor is planning to take down an oak tree in the spring, and I'm trying to guesstimate how much space I'd need to store the wood. The trunk is easy enough to calculate; I haven't measured it, but if it were about 20" in diameter and 15 feet tall, that would be about 33 cubic feet of solid wood. I found a state government document suggesting that S&S firewood is about 70% wood and 30% air space, so that trunk should be a little over a third of a cord. But the geometry gets unwieldy when you start looking at the branches. Is there a rule-of-thumb sort of ratio between the amount of wood in the trunk and the amount in the tree's crown?