Diameter of a tree or log is a straight line passing through the pith. In case of eccentric bole, it is the average of the two diameters, one along major axis and other perpendicular to it. Diameter at breast height (dbh) is defined as the average stem diameter outside bark at a point 4.6 ft. (1.37m) above ground.

Diameter Measurement of logs: In logs, diameters are measured at thick end and thin end or at the middle or at all three places. In stacked logs, diameters are measured only at the end cross-sections.

Diameter Measurement of Standing Trees: In standing trees, diameter can be measured at several places, some within easy reach of man and others beyond it. Among the places within easy reach of standing man BREAST HEIGH (B.H.) is the universally adopted height of measuring diameter.