Clinometer Tree Height (Percent-Slope)
Tree height from a clinometer's percent scale.
Example
You enter
- Horizontal distance to trunk (ft) 100
- Top reading (% slope, + above eye) 58
- Base reading (% slope, - below eye) -4
You get
- Tree height 62 ft
- Height above eye level 58 ft
Details, formula, and sources
Standing a horizontal distance D from the trunk, read the percent slope to the top and to the base, both signed (+ above eye, - below); H = D x (top% - base%)/100. At 100 ft with a +58% top and a -4% base (base below eye) the tree is 62 ft. When the base is below eye its height adds; uphill above eye it subtracts. Percent = 100 tan(angle) for a degree scale. A field estimate; lean and a hidden top add error.
H = D x (top% - base%)/100, D the horizontal distance and top%/base% the signed percent-slope clinometer readings (+ above eye level, - below). above_eye = D x top%/100; below_eye = D x base%/100. Percent = 100 x tan(angle).
Standard forest mensuration / hypsometry (percent-slope clinometer method), USDA Forest Service practice, by name.
The percent-slope tree-height relation is public forestry mensuration.
Estimate. AHJ and licensed professional govern.
Field names used by the API: horizontal_distance_ft, top_reading_pct, base_reading_pct, tree_height_ft, above_eye_ft
- Signed readings percent slope, + above eye level and - below; height = D x (top - base)/100forest mensuration
- Horizontal distance D is the true horizontal distance to the trunkhypsometry method
- Straight stem top directly above base; lean and hidden tops add errorfield-estimate caveat