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Measuring a Tree

Measuring a Tree

Diameter at breast height, or DBH, is the standard for measuring trees. DBH refers to the tree diameter measured at 4.5 feet above the ground. DBH can be measured as follows using a string, a measuring tape, a thumb tack, and a calculator:
  1. With the measuring tape, measure 4.5 feet up the trunk of the tree from the ground. Use a thumb tack to mark the height on the tree.
  2. Wrap your string around the tree trunk at 4.5 feet. Make sure the string is straight and tight around the trunk, and mark or cut the circumference on the string.
  3. Measure the length of string to get the circumference of the tree.
  4. Convert the circumference measurement to diameter by dividing the circumference by pi (3.14).
For measuring DBH of single trunk trees and trees with an angle or on slop, please see figures below:

For multi-stemmed trees, the size is determined by measuring all the trunks, and then adding the total diameter of the largest trunk to one-half the diameter of each additional trunk (see figure below). A multi-stemmed tree has trunks that are connected above the ground and does not include individual trees growing close together or from a common root stock that do not have trunks connected above the ground.