Tree Height Calculator
Estimate how tall a tree, pole or building is without climbing it. Stand back, measure the angle to the top and your distance from the trunk, or compare its shadow with a stick's shadow.
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Horizontal distance, measured on level ground.
From a clinometer or phone level app, measured at eye level.
Ground to eye: about 5.2–5.5 ft (1.6–1.7 m) for an adult.
From the trunk base to the tip of the shadow.
How to use the Tree Height Calculator
- Pick a method: distance + angle if you have a clinometer or phone level app, or the shadow method on a sunny day.
- Measure the distance from where you stand to the base of the trunk on level ground.
- Sight the treetop and read the angle above horizontal, then enter your eye height.
- Or measure shadows: a stick of known height, its shadow, and the tree's shadow at the same time.
- Read the height and check the angle table to see how sensitive the result is.
Tree height formulas
Clinometer (angle) method: height = d × tan(θ) + eye height, where d is the horizontal distance to the trunk and θ is the angle from horizontal up to the top. Example: 30 m away, angle 32°, eye height 1.6 m → 30 × tan 32° = 30 × 0.6249 = 18.75 m, plus 1.6 m = 20.35 m.
Shadow method: height = tree shadow × stick height ÷ stick shadow. A 1 m stick casting a 1.5 m shadow while the tree casts an 18 m shadow gives 18 × 1 ÷ 1.5 = 12 m.
Tips: sight the highest point that sits above the trunk (not the tip of a branch closer to you), measure distance horizontally, and repeat from a second spot to check.
Tangent values for common sighting angles
Height above your eyes = distance × tan(angle). This table shows the multiplier and the height above eye level at 100 ft (or 100 m) away.
| Angle | tan(angle) | Height above eye at 100 units |
|---|---|---|
| 20° | 0.364 | 36.4 |
| 25° | 0.466 | 46.6 |
| 30° | 0.577 | 57.7 |
| 35° | 0.700 | 70.0 |
| 40° | 0.839 | 83.9 |
| 45° | 1.000 | 100.0 |
| 50° | 1.192 | 119.2 |
| 55° | 1.428 | 142.8 |
| 60° | 1.732 | 173.2 |
| 70° | 2.747 | 274.7 |
Frequently asked questions
How do you calculate tree height with an angle?
Multiply the horizontal distance to the trunk by the tangent of the angle to the top, then add your eye height. At 50 ft and 40°: 50 × tan 40° = 50 × 0.8391 = 41.95 ft, plus 5.3 ft eye height = about 47.25 ft.
What is the 45 degree trick for measuring a tree?
Walk away from the tree until the angle to the top is exactly 45°. Because tan 45° = 1, the tree's height above your eyes equals your distance from the trunk, so height = distance + eye height.
How does the shadow method work?
The sun's rays hit the tree and a nearby stick at the same angle, so their heights and shadows form similar triangles. Tree height = tree shadow × (stick height ÷ stick shadow). Measure both shadows within a few minutes of each other.
How can I measure the angle with my phone?
Many phones have a built-in or free level / measure app that shows tilt in degrees. Hold the phone's edge along your line of sight to the treetop and read the angle above horizontal. A dedicated clinometer is more precise.
How accurate is a clinometer tree height measurement?
With careful readings on level ground, results are typically within a few percent. Errors grow at steep angles, on slopes, and when the top is hard to see or the tree leans. Standing at a distance where the angle is 30°–50° gives the best accuracy.
What if the ground is sloped?
This calculator assumes level ground with the angle measured from your eye level. On a slope, use the horizontal distance (not the distance along the ground) and measure an angle down to the base as well, or move to a level spot.
Can I use this for buildings and poles?
Yes. The same trigonometry works for any tall object whose base you can reach, such as a building, flagpole, cliff edge or tower.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.