How to Calculate the Volume of a Douglas Fir Tree

A Douglas fir is any tree in the Pseudotsuga genus, which contains five species. These conifers have very strong wood with many uses in the construction industry. The volume of a Douglas fir tree is an essential factor in determining the amount of lumber the tree can provide. The calculation of this volume uses the diameter of each end of the tree and the length of the tree.

Tape measure
Calculator

Instructions

- 1
  Measure the diameter of the large end of the Douglas fir tree with a tape measure, not counting the bark. Assume for this example that the diameter of the large end of the tree is 2 feet.
- 2
  Measure the diameter of the small end of the Douglas fir tree, not counting the bark. Assume for this example that the diameter of the small end of the tree is 1 foot.
- 3
  Add the diameters of the Douglas fir tree together and divide this sum by 2 to find the average diameter of the tree. The large diameter is 2 and the small diameter is 1, so the average diameter of the tree is (2 + 1) / 2 = 1.5.
- 4
  Measure the length of the Douglas fir tree with a tape measure. Assume for this example that the length of the tree is 112 feet.
- 5
  Calculate the volume of the Douglas fir tree with the equation V = P x (D / 2)^ 2 x H. V is the volume of the tree, P is the value of pi, D is the average diameter of the tree and H is the height of the tree. Pi is a constant equal to about 3.142, the average diameter of the tree is 1.5 feet and the height is about 112 feet. The volume of the tree in this example is V = P x (D / 2)^ 2 x H = 3.142 x (1.5 / 2)^2 x 112 = 197.9 cubic feet.

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