Get Doyle Tree Scale Form Class 78

The Doyle rule is the most common rule used in hardwood log scaling in Tennessee. Edward Doyle developed this rule prior to 1850. This rule estimates the volume based on log length, diameter, slabs, edgings, shrinkage and production of sawdust.

For example, a 20-inch DBH oak tree with a merchantable height of 2½ logs contains 260 board feet Doyle rule or 350 board feet International 1/4-Inch rule.

The Doyle rule is the most common rule used in hardwood log scaling in Tennessee. Edward Doyle developed this rule prior to 1850. This rule estimates the volume based on log length, diameter, slabs, edgings, shrinkage and production of sawdust.

To use the scale, first measure the average diameter of the small end of the log inside the bark (in inches). Locate that row on the scale. Next, measure the length of the log (in feet). Move over on the scale to that length column.

Much of the timber industry operates with the Doyle rule, while some use the International ¼” rule. It is commonly understood that the Int. ¼” rule is the more accurate, in that Doyle underestimates lumber volume, particularly in the smaller-diameter trees.

The Doyle Rule (Table 1) is the most widely used rule, especially on private timber in the east and south. The formula is simple and easy to remember. This formula says to subtract four inches from the diameter for slabs and edgings, square the result, and adjust for log length.

"Form class is the percentage ratio between the diameter inside the bark at. the top of the first 16' log and the diameter outside the bark at DBH (4 1/2. feet above the ground) For example, a tree with a first log scaling diameter. 16" and a DBH of 20" the tree has a form class of (16/20 X 100) 80.