Large Trees ~ Diamter Breast Height

Trunk diameter on large trees is measured at “breast height” which is 4-1/2 feet above the ground, and is more commonly referred to as DBH or Diameter Breast Height.

To find the DBH, stand next to the trunk of the tree and measure at 4.5 ft. above ground. Wrap a measuring tape around trunk and make sure tape is level. Record the circumference in inches.

Diameter is the relationship between the circumference of the a circle (in this case the trunk) and the number π (3.14).

It can be expressed as: Diameter = Circumference ÷ π


  1. The circumference of the tree is measured at 46.5 inches,
  2. Diameter = 46.5 ÷ 3.14
  3. Diameter = 14.8caliper

Small Trees ~ Caliper

Smaller nursery-sized trees that are readily transplanted are usually measured by their “trunk caliper” (diameter) anywhere from 6 to 12 inches above the soil surface, depending on their caliper size.

Example: a 2 to 2-1/2 inch caliper tree is measured 6 inches above the ground.