PB1650 Understanding Log Scales and Log Rules

A necessary step in determining the value of timber at the mill is establishing the estimated volume by standard scaling practices. Examples of scaling practices include measuring the weight of pulpwood to estimate the volume and measuring the dimensions of hardwood sawlogs, along with applying a log rule to determine how much lumber can be sawn from the log. This publication describes common methods of log scaling and log rules used in Tennessee. Scaling estimates the log volume on a board foot, cubic foot, linear foot or cord basis. In scaling pulpwood or chipwood, the volume of available material is usually estimated from the weight of the product, where moisture content, species and other factors are considered. For logs that are to be processed into lumber, log rules are usually applied to estimate the total volume (expressed in board feet) of lumber that can be sawn. A board foot is equivalent to a 1 inch thick by 12 inches long by 12 inches wide, or a 144 cubic-inch piece of wood. Scaling methods are estimates of volume; therefore, variability exists between the different methods based on log shape, density, size, taper, moisture content and human error