How Do I Calculate Quadratic Mean Diameter?

Calculating quadratic mean diameter, a conventional measure of the average tree diameter in a stand, requires estimates of the stand's basal area per acre and trees per acre. Basal area per acre, a measure of the stand's stock, consists of the average of the sum of the cross-sectional area of all of the trees taken at 4 1/2 feet above ground level.

Step 1

Press "(" on the calculator.

Step 2

Press "(" again then enter the basal area per acre figure.

Step 3

Press "/" then the trees per acre figure followed by ")."

Step 4

Press "/" again and enter "0.005454." Press ")."

Step 5

Press the "x to the power of y" key, an italic "x" with "y" in superscript above it.

Step 6

Enter "0.5" and press the equals button. The display will show the quadratic mean diameter in inches, the traditional measurement used.