Tree Height Calculator
Estimate the height of any tall object (tree, building, pole) using trigonometry. Measure the horizontal distance and angle of elevation to calculate height. This method is used by foresters, arborists, and surveyors.
Horizontal distance from tree to measurement point
Angle between horizontal and line of sight to tree top
Your eye height from ground (default 5.5 ft)
How does the tree height calculator work?
This calculator uses trigonometry to find tree height. You measure the horizontal distance from the tree, then the angle of elevation to the top using a clinometer or smartphone app. The formula is: Tree Height = Distance × tan(Angle) + Eye Height. The tan function converts the angle to a slope ratio, which multiplied by distance gives the vertical height.
What tools do I need to measure the angle?
You can use a smartphone with a clinometer app (many free apps available), a dedicated clinometer, or even the built-in level app on iPhones. Hold your phone flat against a board pointed at the tree top, or hold the phone itself and look at the top through the camera. Some apps allow you to input the angle directly.
How accurate is this method?
The trigonometric method is quite accurate when measured correctly. Typical errors are ±2-5% depending on your angle measurement accuracy. To improve accuracy: measure distance precisely using a tape measure or laser distance meter, take multiple readings and average them, stand on level ground, and ensure you're sighting the actual tree top, not a branch. Errors in angle measurement are amplified at greater distances.
Why do I need to add eye height?
You measure the angle from your eye level, not from the ground. If you're 5.5 feet tall and looking at the tree top at a 45° angle, your calculation gives height above your eye, not the ground. Adding your eye height gives the true ground-to-tree-top height. Average eye height is about 5.5 ft (1.68 m) for adults.
What if I'm on a slope?
For sloping terrain, measure horizontal distance (not slope distance) from the tree. The most accurate method is to measure on level ground perpendicular to the tree, or use a surveying approach with two measurements from different distances. Some advanced methods use Depression (looking down) to measure a second angle and calculate relative elevations.
Can I use this for buildings too?
Yes! This method works for any tall vertical object: buildings, flagpoles, cell towers. Just ensure you can see the top clearly and measure an accurate angle. For very tall objects, you'll need to be far enough away that your angle is measurable (typically 15-60° for best accuracy).