 Diameter at breast height, or DBH, is one of the most commonly used terms in forestry. The industry standard measures DBH on the outside of a tree at 4.5 feet above the ground on the uphill side. Diameter is the cross-sectional width of a tree, but because we must measure the circumference of a standing tree, we use a special tape. This tape is called a diameter tape, or D-tape. It has markings that have been calibrated to allow the user to measure diameter directly from a measure of the circumference. Other specialized tools to measure DBH include a Biltmore stick or tree calipers. To measure DBH on your own without using one of these specialized tools, stretch a string or measuring tape around the tree to determine the circumference in inches. Then, divide the circumference by 3.14 or pi to get the diameter measurement in inches. Tree deformities such as knots, cankers, and forks can potentially alter where DBH is measured on a tree. If any of these occur at 4.5 feet on the tree, measure the tree diameter above this point depending on the type of deformity. Forked trees are handled differently depending on whether the fork originates above or below 4.5 feet. For example, if a tree forks below 4.5 feet, consider it two trees. If the fork is above 4.5 feet, consider it one tree. The diameter at breast height and the height of the tree are the two most important measurements in forestry and make up the foundation for calculating weight, volume, and subsequent value of individual trees or forest stands.