We want to make it easy for you to be a successful tree care professional and you need easy access to a tape measure. Chemical dosages are based on the Diameter (in inches) of the tree at Breast Height (“DBH”). DBH is the outside bark diameter of the trunk at 4.5 feet (1.37 m) above the ground on the uphill side of the tree. For the purposes of determining breast height, the ground includes the duff layer that may be present, but does not include unincorporated woody debris that may rise above the ground line. The diameter is determined by measuring the circumference of the tree at DBH and dividing the circumference (in inches) by three (3). To determine DBH for multi-stemmed woody ornamentals, measure the DBH for each stem or branch and add together for the total DBH per tree. Our website has a quick and easy application calculator that can assist you in planning the amount of chemical you will use for a tree. For more information, click here.