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Tree Calculations

Calculating Diameter Breast Height

Diameter Breast Height (DBH) is the standard used to measure the size of a tree. DBH is measured at 54 inches above ground.

Diagram showing how to measure a tree by first finding its diameter breast height (DBH). First tree shows a measuring stick going from the ground to 54 inches up the tree trunk. The second tree shows the 54-inch mark is where the diameter is to be measured.

How to measure your tree's diameter

  1. Use a soft measuring tape. Wrap it around each branch at 54 inches (4.5 feet) to find the circumference of each one.
  2. Write down the circumference for each branch so you can use it for the below calculations.
  3. For each branch, enter the circumference into Calculator 1 below to find the DBH of the branch.
  4. Write down the DBH for each branch so you can enter them into Calculator 2.
  5. Enter the DBH of each branch into Calculator 2 below to find the equivalent DBH of the tree.