DBH (diameter at breast height)
Also called: diameter at breast height, trunk diameter
The standard way to measure a tree's trunk: its diameter at 4.5 feet above the ground. Tree-removal permits and price tiers are often set by DBH.
To measure DBH, wrap a tape around the trunk 4.5 ft (about 1.4 m) above the ground on the uphill side, then divide the circumference by π (3.14). A 38-inch circumference is roughly a 12-inch DBH.
DBH matters for two reasons. Many cities set their tree-removal permit threshold by it — commonly anywhere from 6 to 12 inches — so a tree above the line needs paperwork before it comes down. And tree services use it alongside height to size a job: a thick trunk means more cutting, heavier sections, and more wood to haul.