Tree Height Calculator
Estimate a tree's height without climbing it using one of three field-proven methods: the angle method (trigonometry with a clinometer or phone app), the shadow method (similar triangles using shadows on a sunny day), or the stick method (a handheld rod and arm-length geometry). Choose your method and unit system, enter your measurements, and the height updates instantly along with a step-by-step worked calculation.
Formula
Worked example
Example (angle method): Observer stands 20 m from a tree on flat ground, measures angle to treetop at 40 degrees, eye height 1.6 m. Tree height = tan(40 degrees) x 20 + 1.6 = 0.8391 x 20 + 1.6 = 16.78 + 1.6 = 18.4 m. Shadow example: tree shadow 15 m, person 1.75 m tall casts a 1.2 m shadow, so tree height = 1.75 x 15 / 1.2 = 21.9 m.
How to measure a tree without climbing it
Three classic field methods let you estimate tree height safely from the ground. The angle method is the most widely used professional approach: stand a known horizontal distance from the tree, use a clinometer (or a smartphone app such as Theodolite) to measure the angle from your eye level up to the treetop, and apply basic trigonometry. The shadow method exploits similar triangles: on a sunny day, compare the length of the tree's shadow to the shadow cast by an object of known height. The stick method uses your arm as a measuring instrument: hold a rod vertically at arm's length and walk back until the rod just covers the tree, then apply the same similar-triangle ratio. All three methods give estimates within about 5-10% of the true height when measurements are careful and the ground is reasonably flat.
The angle (trigonometric) method - formulas for every terrain
When the tree base is at the same level as you, the height above your eye = tan(angle-to-top) x horizontal distance, and you add your eye height to get the ground-to-tip total. If the tree's base is lower than you (you are above it on a slope), the full height equals (tan(angle-to-top) + tan(angle-to-base)) x horizontal distance. If the base is higher than you, it equals (tan(angle-to-top) - tan(angle-to-base)) x horizontal distance. The ideal angle to the treetop is 30-60 degrees: angles below 20 degrees amplify small distance errors, while angles above 70 degrees amplify angle-reading errors. A good rule of thumb is to stand back a distance roughly equal to the expected tree height.
Shadow method and stick method - quick no-equipment options
Shadow method: place a metre stick (or yourself) upright on flat ground next to the tree's shadow. Measure both shadows at the same moment because the sun moves. Tree height = (reference height x tree shadow) / reference shadow. This ratio works because sunlight hits both objects at the same angle, so the triangles formed are similar. The stick method: hold a straight rod vertically at arm's length, step back until the rod exactly subtends the full height of the tree. Tree height = (stick length / arm distance) x distance from eye to tree base. This is the same similar-triangle principle but does not require sunshine. Accuracy depends on holding the stick perfectly upright and measuring the arm distance carefully from your eye, not from your shoulder.
Accuracy, terrain, and professional-grade methods
Standard angle-and-tape measurements assume the tree grows vertically and that you can correctly identify the topmost tip. On slopes, measuring horizontal distance (not slope distance) is critical: using slope distance without correction overstates the result. Major forestry agencies now recommend the sine-based method using a laser rangefinder plus clinometer, which measures the slant distance directly to the treetop and applies H = D1 x sin(angle-top) - D2 x sin(angle-base). This avoids the need to stand directly below the crown and is far more accurate when the tallest branch is offset from the trunk. LiDAR instruments measure height to within about 1 metre. For most garden, landscape, and informal forestry uses the tangent method described here is accurate enough.
Typical mature heights of common tree species
| Species | Typical mature height (m) | Typical mature height (ft) | Size class |
|---|---|---|---|
| Apple (Malus domestica) | 3-9 | 10-30 | Small |
| Cherry (Prunus avium) | 5-15 | 16-50 | Small-Medium |
| Silver Birch (Betula pendula) | 10-25 | 33-82 | Medium |
| Rowan (Sorbus aucuparia) | 5-15 | 16-50 | Small-Medium |
| Hawthorn (Crataegus monogyna) | 5-14 | 16-46 | Small-Medium |
| Sycamore (Acer pseudoplatanus) | 20-35 | 66-115 | Large |
| English Oak (Quercus robur) | 20-40 | 66-131 | Large |
| Red Oak (Quercus rubra) | 18-25 | 59-82 | Large |
| European Beech (Fagus sylvatica) | 25-40 | 82-131 | Large |
| Horse Chestnut (Aesculus hippocastanum) | 20-35 | 66-115 | Large |
| Norway Spruce (Picea abies) | 30-50 | 98-164 | Large-Very Large |
| Scots Pine (Pinus sylvestris) | 20-35 | 66-115 | Large |
| Douglas Fir (Pseudotsuga menziesii) | 30-80 | 98-262 | Very Large |
| Sitka Spruce (Picea sitchensis) | 40-70 | 131-230 | Very Large |
| Coast Redwood (Sequoia sempervirens) | 60-115 | 197-377 | Giant |
Approximate heights for healthy, mature specimens growing in favorable conditions. Actual heights vary by soil, rainfall, competition, and climate.
Frequently asked questions
What is the most accurate way to measure a tree's height?
The sine-height method using a laser rangefinder and clinometer is the most accurate field technique, giving results within about 30 cm of a climber-verified measurement. The standard tangent method with a tape measure and clinometer is the next best option and is accurate to within about 5% when measurements are careful. The shadow and stick methods are simpler but can carry 5-15% error depending on terrain and technique.
How do I measure the angle to the treetop without a clinometer?
Many free smartphone apps measure inclination angles using the phone's built-in accelerometer and gyroscope. Apps such as Clinometer (iOS and Android), Theodolite, or even the built-in Measure app on recent iPhones can be used. Hold the phone with the screen facing you, sight along the top edge toward the treetop, and read the angle from the display. For best results, hold the phone steady or rest it against a rigid object, and confirm the angle by taking several readings.
Does the shadow method work on a slope?
Not reliably. The shadow method assumes both objects and their shadows lie on the same flat plane. On sloping ground the shadow length is affected by the incline, which distorts the ratio. The angle method or the stick method are better choices when the ground is uneven.
Why does the formula change depending on whether the tree base is higher or lower than me?
When you are on flat ground at the same level as the tree base, tan(angle-up-to-top) x distance gives the height above your eye, and you add your eye height to get the full tree height. When the base is below you (you are above it), you are already looking down to the base as well as up to the top, so both angles contribute and you add the tangents. When the base is above you (the tree grows on a higher slope), you subtract the base angle because the base elevation reduces the apparent height. Choosing the correct terrain setting in this calculator selects the right formula automatically.
How close should I stand to get the best measurement?
Aim for an angle to the treetop of between 30 and 60 degrees, which means standing roughly 0.6 to 1.7 times the expected tree height away. For a 20 m tree that suggests a distance of about 12-34 m. Standing too close inflates small angle errors; standing too far means you are measuring mostly horizontal distance and a small angle, both of which magnify imprecision.
Can I use this calculator for buildings or other structures?
Yes. All three methods work for any vertical object whose top you can sight clearly. The angle method works particularly well for buildings, antenna masts, or cliff faces. The shadow method requires the object to cast a clear shadow and the ground to be flat.
What is the tallest tree ever measured?
Hyperion, a coast redwood (Sequoia sempervirens) in Redwood National Park, California, was measured at 115.9 m (380.3 ft) in 2006, making it the tallest known living tree. The theoretical maximum height any tree can reach is estimated at around 122-130 m, limited by the energy required to lift water that high against gravity.