Diameter at breast height, or DBH, is a standard method of expressing the diameter of the trunk or bole of a standing tree. DBH is one of the most common dendrometric measurements.

Tree trunks are measured at the height of an adult's breast, which is defined differently in different countries and situations. In continental Europe, Australia, the UK, and Canada the diameter is measured at 4.2 feet (1.3m) above ground. In The US, New Zealand, Burma, India, Malaysia, and South Africa, breast height diameter is measured at a height of 4.5 feet (1.4m). Ornamental trees are usually measured at 4.9 feet (1.5m) above ground.