Tree Height Calculator

How to use this calculator

1. Choose angles or shadows and select the unit beside each relevant distance. Compatible length units can be mixed; the calculator converts them before applying the formula.
2. For angles, measure horizontal distance and signed elevation angles from the same observation point. Angles below eye level are negative.
3. For shadows, measure a known reference and the tree’s shadow at the same time on level ground.

Formula and method

For the assumptions behind these results, read the explanation below. You can also explore Tree Diameter and Tree Age.

Use a common horizontal reference

The angle method describes the vertical positions of the top and base relative to the observer’s horizontal sight line. Subtracting those positions produces the full tree height. A base below that line has a negative angle, so subtracting it adds the missing lower portion. A base uphill may have a positive angle.

Distance must be horizontal distance to the trunk, not distance measured along a steep slope or a slanted line toward the crown. Both angles must come from the same observation point. Measuring the base angle directly removes the need to separately enter eye height. Angles close to 90 degrees are especially sensitive to small measurement errors.

When shadows are a practical alternative

Under the same sunlight, upright objects on level ground produce similar triangles. The ratio of height to shadow length is therefore shared by the tree and a reference object. Measure both shadows at nearly the same time because the Sun’s position changes. The reference height must be its vertical height above the ground.

A sloped surface, a leaning tree, an obscured shadow tip, or a crown projecting far from the trunk can undermine the simple geometry. A distant high branch may also be mistaken for a point directly above the measured base. Treat the result as a field estimate and repeat measurements from another position when precision matters.