[header] How to measure diameter at breast height (dbh ) [title] Measure 4.5 ft (1.3 m) above the ground. [step] Use yourself as a human measuring stick by locating this point on your body before entering the field. If the tree is on a slope, measure from the highest point of the ground. 
[title] Wrap your diameter tape around the tree's trunk at the determined height. [step] Most tapes have a hook attached that you can use to anchor the end of the tape if the trunk is too big to wrap your arms around.