Calculate diameter at breast height from a tape measurement around the trunk.
| DBH | – |
Use this calculator to obtain diameter at breast height (DBH) from the circumference of the trunk. Measure around the bark at about 1.3 m (4.5 ft) above the ground, then convert the girth to a diameter.
The calculation is: DBH = circumference ÷ π. Circumference can be entered in centimetres (cm) or inches (in); the diameter is shown in the same unit. Measure on the uphill side if the ground slopes, and above any basal flare or root collar.
This is the standard forestry conversion from girth to diameter. It assumes a circular cross-section. An oval, forked, or burred stem will not match a perfect circle, so the result is an equivalent diameter, not a true geometric diameter in every direction.
Circumference: Tape around the trunk at about 1.3 m, snug but not crushing the bark. Enter the value in cm or in.
DBH: Diameter at breast height, in the same length unit as the circumference.
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