Tree Height Calculator
Work out how tall a tree is from a clinometer angle and distance, or from the length of its shadow, without climbing it or cutting it down.
🌱 What is the Tree Height Calculator?
Tree height measurement is the practice of working out how tall a standing tree is using trigonometry rather than a tape stretched up the trunk. Two field methods dominate. The tangent method uses a clinometer or a phone inclinometer to read the angle from your eye up to the top of the tree, combines it with the horizontal distance to the trunk, and solves the resulting right triangle. The shadow method needs no instrument at all: it compares the length of the tree's shadow with the shadow of an object whose height you already know, and scales up by simple proportion.
Height matters in more places than people expect. Timber buyers pair it with trunk diameter to look up merchantable volume, because volume tables are indexed on both. Utility crews and municipal risk assessors need it to decide whether a tree can reach a power line, a roof or a road if it fails. Carbon inventory protocols feed height and diameter into allometric equations that estimate above-ground biomass. Arborists use it to plan rigging and to size drop zones before a removal. Champion-tree registries score entries on height, girth and crown spread combined.
The most common misconception is that a steeper sighting angle gives a better reading. The opposite is true past about 60 degrees, where the tangent function climbs so steeply that half a degree of hand wobble can move the answer by several feet. The second frequent error is sighting a branch tip that happens to be closest to you rather than the genuinely highest point of the crown, which on a spreading hardwood can overstate the tree substantially. A third is pacing the slope distance along a hillside and treating it as horizontal distance.
This calculator covers both field methods. The clinometer mode handles level ground by adding your eye height, and sloping ground by taking a second angle down to the base of the tree, so the geometry stays correct whichever side of the slope you stand on. The shadow mode reports the sun's elevation angle alongside the height, which tells you immediately whether conditions were good: a sun between 30 and 50 degrees gives the most reliable readings. Both modes report the answer in feet and metres at once, and chart how sensitive your result is to the angle you read.
📐 Formula
📖 How to Use This Calculator
Steps
💡 Example Calculations
Example 1 — Backyard Tree on Level Ground
Standing 50 ft back, clinometer reads 40 degrees, eye height 5.5 ft
Example 2 — Tree Downhill on a Slope
Horizontal distance 80 ft, 35 degrees up to the top, 10 degrees down to the base
Example 3 — Shadow Method With No Instrument
Tree shadow 45 ft, a 6 ft person casts an 8 ft shadow
Example 4 — Metric Clinometer Reading at 45 Degrees
Standing 20 m back, angle 45 degrees, eye height 1.6 m
Example 5 — Metric Shadow Reading With a Marked Pole
Tree shadow 30 m, a 1.7 m pole casts a 2.5 m shadow
❓ Frequently Asked Questions
🔗 Related Calculators
How do you measure the height of a tree with a clinometer?
Measure the horizontal distance to the trunk, sight the top of the tree, and read the angle. Height above eye level is distance multiplied by the tangent of that angle, then add your eye height. At 50 feet with a 40 degree reading and a 5.5 foot eye height, the tree is 47.45 feet tall.
How do you measure tree height using shadows?
Measure the tree's shadow, then measure the shadow of an object whose height you know, such as yourself or a marked pole. Tree height equals reference height multiplied by tree shadow divided by reference shadow. A 45 foot shadow with a 6 foot person casting an 8 foot shadow gives 33.75 feet.
What is the tangent method for tree height?
The tangent method treats the sight line, the horizontal distance and the tree as a right triangle. Height above eye level is D multiplied by tan of the sighting angle. It is the standard field method and is exact as long as the distance is truly horizontal and you sight the actual highest point.
Do I need to add my eye height?
Yes, whenever you are standing on the same level as the base of the tree. The tangent calculation only gives the part of the tree above your eye, so the portion between the ground and your eye has to be added back. On sloping ground use the angle down to the base instead.
How do I measure a tree on sloping ground?
Take two angles from the same spot: one up to the top and one down to the base. Height is the horizontal distance multiplied by the sum of the two tangents. Switch the base reference to angle mode and enter both readings, and the calculator handles the geometry.
How accurate is the shadow method?
On flat, open ground with both readings taken within a minute of each other, it is typically within 5 to 10 percent. Accuracy falls off badly when the sun is low, because small errors in a long shadow translate into large height errors, and when the ground under either shadow is not level.
What is the best time of day to use the shadow method?
Mid-morning or mid-afternoon, when the sun sits roughly 30 to 50 degrees above the horizon and shadows are between one and two times the height of the object casting them. At noon in summer shadows are too short to measure precisely, and near sunset they run too far and over uneven ground.
Why is my clinometer reading giving a height that seems too tall?
The two usual causes are sighting a nearer branch instead of the true top, and using a paced slope distance in place of the horizontal distance. Both inflate the answer. A third cause is standing too close, where a steep angle magnifies every small error in the reading.
Can I use a phone app instead of a clinometer?
Yes. Phone inclinometer apps read the device's accelerometers and are usually accurate to about half a degree, which is good enough for most work. Rest the phone against a straight edge rather than holding it freehand, and take three readings and average them.
What is the difference between the tangent method and the sine method?
The tangent method uses horizontal distance and assumes the top of the tree sits directly above the base. The sine method uses a laser rangefinder to measure the slope distance to the actual top, so it stays correct for leaning trees and off-centre crowns. The sine method is preferred for record measurements.
How do I convert tree height from feet to metres?
Divide by 3.2808. A 47.45 foot tree is 14.46 metres. The calculator shows both units at once, so you can enter your measurements in whichever system your tape uses and read the answer in either.
Does the stick method work as well as these two?
The stick method, where you hold a stick of arm's length upright and back away until its tip and base line up with the tree's top and bottom, is quick but crude. At that point the distance to the tree roughly equals its height. Expect errors of 15 to 20 percent, so use it only as a sanity check.