Tree Diameter Calculator

No. 4.5 ft equals 1.3716 m, while a metric breast-height convention uses 1.30 m. The chosen standard records where you measured. Unit switching converts the existing length; changing the standard cannot remeasure the tree or correct for taper.

Diameter × growth factor is a rough educational heuristic. Climate, soil, competition, tree condition and site history can strongly change diameter growth. The preset factors are assumptions, not validated site-specific growth models or uncertainty bounds. NIST describes ring analysis and cross-dating for age measurement. The rings in this diagram are decorative.

Follow the measurement rules of your inventory protocol. US Forest Service guidance handles stems forked below breast height separately and adjusts the measurement position around swellings. For an irregular or elliptical section, circumference ÷ π is a circular-equivalent diameter; the calculated circular area need not equal the true area.

Not on its own. This result is one stem’s circular area at the recorded height, not stump area, wood volume, stand basal area per hectare/acre or stored carbon. Volume and carbon models need additional data such as height, species, form, density and appropriate model assumptions.

DBH from circumference or circumference from DBH, radius and circular basal area per tree. Optional age is a separate growth-factor heuristic. Geometry stays the same when you change species or the age factor.

Enter a circumference measured with a normal tape or a diameter measured directly, in inches or centimetres. A diameter tape already reads diameter, so use DBH input mode for that reading. Select the height standard actually used and, if desired, an age-factor assumption.

Diameter = circumference ÷ π; circumference = π × diameter; radius = diameter ÷ 2; basal area = π × radius². Age approximation = diameter in inches × factor in years per inch. The conversion is 1 in = 2.54 cm.

Measurement height, outside-bark conventions, trunk irregularity, units and display rounding can all matter. Age factors are rough assumptions and may differ between educational tables; one factor is not an accurate universal age model.

Yes. Mode changes convert between circumference and diameter while preserving the same circular geometry; unit changes preserve physical size. Species and factor changes affect age only. The measurement-height standard changes the recorded context, not your measured length.

Educational factor tables use white oak 5.0 and red maple 4.5 years per inch; one worksheet lists red pine 5.5. These are editable teaching assumptions, not an endorsement or a field-calibrated prediction. The William & Mary teaching notes and the WQED Age of a Tree worksheet provide context. Select No age estimate to omit this heuristic.