Tree Height Calculator (Clinometer, Stick & Shadow Methods)

How it works

Clinometer: height = D × tan(top angle) − D × tan(base angle) (base angle negative when below eye level); shadow: height = tree shadow × reference height ÷ reference shadow; stick: height ≈ distance + eye height

Every tree-height method is a triangle. With a clinometer (or a phone’s inclinometer) you pace or tape a horizontal distance, read the angle to the top and the angle to the base, and the tangents give the heights above and below eye level — adding them handles trees on slopes. Foresters use the percent scale because at a standard 20 m or 100 ft distance the reading converts to height by simple division. The shadow method uses similar triangles with your own shadow and needs flat ground and a distinct top shadow; the stick method — holding a stick equal to your arm length upright and walking back until it spans the tree — gives a quick 45° estimate that is plenty for deciding whether a tree can hit the house. Distance should be measured horizontally and roughly equal to the height for best accuracy.

Worked example

From 30 m, 42° to the top and 4° down to the base at 1.6 m eye height: 30 × tan 42° = 27.0 m above eye level plus 30 × tan 4° = 2.1 m below — 29.1 m (95 ft). Keep everyone 44 m back when felling.

Frequently asked questions