Tables for Estimating Board-Foot Volume of Timber


Clement Mesavage, Foresters, Southern Forest Experiment Station, and
James W. Girard, Assistant Director, Forest Survey

USDA-Forest Service

Form Class Volume Tables




Source: C. Mesavage and J.W. Girard. 1946. Tables for estimating board-foot volume of timber. USDA Forest Service, Washington, DC. 94 p.


Note: These tables have been a standard for sawtimber estimation in the South for decades. The tables are based on three basic measurements of trees: diameter breast high, merchantable height, and form class. Although these tables have been in existence for decades, they are still applicable since the three major determinants of tree volume are taken into account.

See Table 4 for average form class by tree species. Typically, fast growing, young trees have a lower form class than slower growing, older trees. Trees grown at closer spacings typically have better form class than those grown at wide spacings.

To increase accuracy of volume estimate, form class can be measured directly on a sample of trees, by either felling trees and measuring appropriate diameters directly (or measure during logging), carefully using a ladder and bark gauge to measure diameter at 17.3 feet above the ground, or using an optical dendrometer (instrument for measuring diameter from a distance) and assuming the same inside bark:outside bark ratio as measured at breast height to estimate inside bark diameter at 17.3 feet. You can also ask a local forester what form class they use when estimating timber. You may also want to ask if this is based on measurements they have observed or on common practice.

Questions or Comments? Contact PFMT.

Most Recent Revision: 09/20/06
Private Forest Management Team
Auburn University, Alabama