How many trees make a cord? Well, it depends on the size of the trees, obviously. I’ve wondered this myself and finally stumbled across this information from the University of New Hampshire’s Cooperative Extension. This 1-page PDF from UNH describes an easy way to estimate the amount of firewood you’ll net by the size and quantity of standing trees.
(Interesting that a single tree 22″ in width can produce a cord)
Picture from Washington Post.
8/29 Update: I found another great resource from the University of Nebraska‘s aggricultural department. It doesn’t include the same level of detail as UNH but has quick summaries on species characteristics including green/dry weights, BTUs, and other characteristics. It also includes safety tips and a cost-comparison of firewood against other fuels such as oil, propane, and natural gas. Link: Heating With Wood: Producing, Harvesting and Processing Firewood