Tree Height Calculator

Background.

Nobody climbs a tree to measure it. Foresters, arborists and big-tree hunters stand on the ground, sight upward and rebuild the vertical distance from geometry; the real choices are which instrument you carry and which assumptions you will accept about the tree.

The tangent method, the forester's standard, uses a clinometer or a phone inclinometer app, a tape run to the trunk, and two readings: one to the top of the crown and one to the base. The sine method, set out in a 2011 USDA Forest Service research note, swaps the tape for a laser rangefinder and uses the straight-line distance to each of those points. The shadow method needs only sunshine and an upright object of known height.

The second reading is what separates a tree measurement from a schoolbook triangle. A sighting to the top gives the crown's height above your eye, and the ground at the trunk is normally several feet below your eye, so a single sighting leaves every tree short by roughly your eye height. Entered as a negative number and subtracted, the base reading adds that piece back, and the result shows both pieces separately.

Accuracy runs sine first, tangent second, shadow last, and the method note beside the answer explains why. You get total height in your own unit plus the 5-foot and 10-foot height classes timber cruisers record. Whether a tree is sound or dangerous is a question for an arborist on site, not for a height figure.

What is tree height calculator?

Total tree height is the vertical distance from the ground at the base of the trunk to the highest point of the crown. Foresters sight the top of the woody structure rather than the last flickering leaf, and on a broad hardwood that high point is often not directly above the trunk. Total height is a different quantity from merchantable height (the usable stem up to a mill's diameter limit) and from height to live crown (where the canopy begins); neither of those is measured here. A forestry clinometer usually carries two scales: a percent scale, which reads rise per 100 units of horizontal run and so is already a tangent, and a topographic scale, which reads height directly in feet when you stand one chain, 66 feet, from the tree.

How to use this calculator.

1. 01Choose the method that matches your equipment, the unit you will measure distances in, and whether your angle readings are percent (most forestry clinometers) or degrees (most phone apps).
2. 02Tangent method: stand at least as far from the trunk as the tree is tall and enter the true horizontal distance. On a slope, first multiply the taped distance by the cosine of the angle to the point where the tape is held.
3. 03Sight the highest point of the crown, then the ground at the foot of the trunk. Enter the base reading as negative whenever the base is below your eye, which it nearly always is; it is positive only when you stand downhill of the tree.
4. 04Sine method: with the laser, record the slope distance and angle to the top, then to the base, using the same sign rule for the base angle.
5. 05Shadow method: on level, open ground, measure the tree's shadow from trunk to tip, then straight away an upright stick or person of known height and its shadow.
6. 06Check the split above and below your eye, and the method note, before relying on the figure for a leaning tree, a spreading crown or a hillside.

The formula.

The tangent method is H = b × (tan θ_top − tan θ_base), where b is the horizontal distance from your eye to the trunk and the angles are measured from horizontal, up positive and down negative. With a percent-scale clinometer each reading p already equals 100 × tan θ, so the arithmetic collapses to H = b × (p_top − p_base) ÷ 100; at exactly 100 feet away, the readings are the heights in feet. The sine method is H = d₁ × sin θ_top − d₂ × sin θ_base, where d₁ and d₂ are the laser's straight-line distances to the top and to the base. For a perfectly vertical tree the two agree, because the slope distance to any point is b ÷ cos θ, and sin θ ÷ cos θ is tan θ: a 100-foot baseline with sightings of 40° up and 5° down gives 92.6588 feet by either equation. They part company when the crown's high point is not over the trunk, because the sine method measures to the point you actually hit while the tangent method projects one. The shadow method is similar triangles: H = h_ref × s_tree ÷ s_ref, and atan(h_ref ÷ s_ref) is the sun's elevation, which is reported in the angle output. Degree readings must lie strictly between −90° and 90°, since the tangent has no value at the vertical; percent readings have no ceiling. A pair of readings that gives zero or negative height is rejected. Feet and metres convert at exactly 0.3048 m per foot. The height classes use the Alabama Cooperative Extension rule, class₅ = 5 × ⌈(H_ft − 2.5) ÷ 5⌉ and class₁₀ = 10 × ⌈(H_ft − 5) ÷ 10⌉, which makes a height ending in 5 round down.

A worked example.

Frequently asked questions.

References& sources.

1. [1]Bragg, D.C.; Frelich, L.E.; Leverett, R.T.; Blozan, W.; Luthringer, D.J. 2011. "The sine method: an alternative height measurement technique." Research Note SRS-RN-22. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 12 p. Source of equation (2) (tangent method, with the explicit convention that the angle to the base is negative when the base is below the observer's eye level, so subtracting a negative produces a positive height component), equation (3) (slope-to-horizontal baseline correction) and equation (4) (sine method). Retrieved 2026-07-31; open access PDF, read in full.
2. [2]Alabama Cooperative Extension System (Auburn University), "Forest Inventory Basics for Family Forest Landowners", Chapter 8, "Measuring Tree Heights" (FOR-2082). Source of the percent-scale clinometer procedure, of the three worked examples and five answer-key results this calculator reproduces exactly, and of the 5-foot and 10-foot height class definitions — "trees measuring between 62.6 and 67.5 are in the 65-foot class" and "trees that are 66 to 75 feet tall are in the 70-foot height class ... heights that end in 5 round down". Used as the independent check on the Forest Service equations. Retrieved 2026-07-31; open access PDF, read in full.
3. [3]Bragg, D.C. 2014. "Accurately measuring the height of (real) forest trees." Journal of Forestry 112(1):51-54. doi:10.5849/jof.13-065. Names the similar triangles and tangent methods as the two approaches that have dominated tree height measurement, traces similar-triangle hypsometers to Tieman (1904), and documents that the tangent method overestimates on leaning stems and offset crowns. Source of the accuracy ordering stated beside the result. Retrieved 2026-07-31; open access PDF, read in full.
4. [4]USDA Natural Resources Conservation Service with Iowa State University NRI Grazing Land, "Measuring Tree Height using a Clinometer". Corroborating field procedure: the topographic scale is read directly at 66 feet and the percent scale at 100 feet, and the base reading is subtracted from the top reading. Confirms the sign convention independently of both Forest Service documents. Retrieved 2026-07-31; open access.