Firewood charts vary by species (ash are taller and straighter than others) and even by region or soil type (trees at the top of a Catskill mountain will be shorter than those in a valley near Oneonta). But if you are looking for "close enough" then I'd recommend this simple chart below. It has been used extensively in central New York by NYSDEC Foresters, and can even be considered a conservative estimate because the tops are gravy. 8" diameter 0.1 cords 10" diameter 0.2 cords 12" diameter 0.25 cords 14" diameter 0.3 cords 16" diameter 0.5 cords 18" diameter 0.7 cords 20" diameter 0.9 cords 22" diameter 1.0 cords To answer the question about the origin, the name "cord" dates back to the early 1600's and refers to a literal cord, or string or rope, that was used to measure bundles of firewood. The size was probably arbitrary, or is at least unknown to us now, but after enough time, units of measurement tend to "stick" around. Has anyone else used a chart to measure standing firewood volume of trees? Got any trick you can share? We'd love to hear from you!