Diameter at breast height, DBH, can be measured quickly by the homeowner. I use a measuring tape like tailors use but a piece of string can do the job also. Using a metal measuring tape like a contractor would use will not give an accurate measurement but can give you a ball park figure if you do not have any other means.
-With a measuring tape, measure 4.5 feet up the trunk of the tree.
-Wrap your tape measure around the tree at that height. Make sure your tape measure or string is tight around the trunk of the tree and take your measurement.
-If using a string, mark the string so you can measure the length to get the circumference.
-Convert the circumference to diameter by dividing by 3.
-Multiply the diameter by $10.00 for trees with diameters between 6-9 inches. Multiply by $9.00 for trees between 10-20 inches and multiply by $11.00 for trees with a diameter of 20 inches and over.
This will give you your estimate. For example: you measure a tree and the circumference is 45 inches. Divide 45 by 3 to get the diameter of 15 inches. Multiply 15 times $9.00 to get an estimate of $135.00.
Below are figures to show you how to measure based on your tree and its location:
Front Range Tree Treatment
For multi-stemmed trees, the size is determined by measuring all the trunks, and then adding the total diameter of the largest trunk to one-half the diameter of each additional trunk (see Figure 80-7). A multi-stemmed tree has trunks that are connected above the ground and does not include individual trees growing close together or from a common root stock that do not have trunks connected above the ground.
When the trunk is at an angle or is on a slope, the trunk is measured at right angles to the trunk 4.5 feet along the center of the trunk axis, so the height is the average of the shortest and the longest sides of the trunk; see Figure 80-5.
When the trunk branches or splits less than 4.5 feet from the ground, measure the smallest circumference below the lowest branch. See Figure 80-6. If the tree has a branch or a bump at 4.5 feet, it is better to measure the diameter slightly below or above the branch/bump.
HOW TO MEASURE A TREE AND GET YOUR ESTIMATE