Height = Distance × tan(angle) + Eye Height
The clinometer method: stand a known distance from the tree, measure the angle to the treetop with a clinometer or phone app, then calculate: Height = distance × tan(angle) + eye height. At exactly 100 ft away, the percent reading on a clinometer equals the height directly. The shadow method: measure your shadow and the tree's shadow simultaneously — tree height = (tree shadow / your shadow) × your height. Laser rangefinder/hypsometers are the most accurate field tools. Average heights: oak 60-80 ft, pine 80-100 ft, redwood 200-350+ ft. The tallest known tree is Hyperion, a coast redwood at 380.3 ft (115.92 m).