Tree Height Calculator
Tree height from distance and clinometer angle.
What it does
Foresters measure trees with right triangles: stand a known distance away, sight the top for the angle, and height is distance times tangent plus eye height. Phone clinometers read angles within a degree, close enough for bragging rights and firewood math.
The tool above takes distance, angle, and eye height in either system. It returns tree height with the other unit beside it.
Level ground makes or breaks the triangle. Uphill stances shrink readings and downhill ones stretch them, so split the difference or move until the base sits level with your feet.
Leaning trunks need two sights. Measure to the top along the lean and note the direction, since vertical height differs from trunk length on tilters.
How to use
- Switch the unit system first: imperial for feet, metric for meters.
- Pace or tape the distance to the trunk.
- Sight the very top with a clinometer app.
- Enter eye height and read the tree.
Formula
- tan(angle)
- Rise per unit of distance at the sighted angle.
- eye height
- Sight line height above the base ground.
Forty five degrees makes height equal distance plus eye, a handy field check: pace until the top reads 45 and read the tape.
Worked example
Example: 50 ft away, 35 degrees, 5.5 ft eyes
Distance 50 ft, angle 35, eye height 5.5 ft.
- Tangent: tan(35°) = 0.70021.
- Above eyes: 50 x 0.70021 = 35.01 ft.
- Total: 35.01 + 5.5 = 40.5 ft.
- Metric: 40.5 x 0.3048 = 12.3 m.
Reference table
| Angle | Height | Angle | Height |
|---|---|---|---|
| 20° | 23.7 ft | 35° | 40.5 ft |
| 25° | 28.8 ft | 40° | 47.5 ft |
| 30° | 34.4 ft | 45° | 55.5 ft |
Limits
- Level ground assumed. Slopes need corrections.
- Leaning trees need lean direction noted.
- Top hidden by canopy reads low.
- App angles run about a degree of error.
Common mistakes
- Measuring slope distance instead of horizontal.
- Sighting a side branch instead of the top.
- Forgetting eye height entirely.
- Standing too close where angles swing fast.
- Ignoring lean on edge trees.
Try it yourself
Quick checks. Answers sit tucked under each question.
100 ft away, 45 degrees, 5.5 ft eyes?
100 x 1 + 5.5 = 105.5 ft.
Metric: 15 m, 35 degrees, 1.7 m eyes?
15 x 0.70021 + 1.7 = 12.2 m.
Questions
How accurate is this method?
Within a few percent on level ground with careful angles. Good enough for estimates.
Do I need a real clinometer?
No. Phone apps read well enough for casual measuring.
What if the ground slopes?
Measure eye height above the base level and correct, or move to level ground.
How do foresters measure precisely?
Laser hypsometers with lean corrections. Tangent math matches closely.
Can I measure buildings too?
Yes. The same triangle sizes anything tall from its base distance.
Why 45 degrees special?
Tangent equals one, so height is distance plus eye with no tables.