Tree height calculator
Type the angle to the top of a tree, the distance from the tree and the eye height to see the tree's height by the tangent method.
Checked against the sources at the bottom of this page on October 8, 2026. Published tables are revised: the source has the last word.
Work it out
How the answer is worked out
Height = the tangent of the angle, times the distance, plus the eye height.
The distance is the level distance to the trunk, and the ground is taken as level between the eye and the foot of the tree.
What the sources say
The University of British Columbia's BC BigTree site writes the sum as h = Tan A times d, plus eye height, where d is the distance from the tree and A is the angle to the top, for working on level ground. It says measurements are more reliable the further back the measurer stands, and that the distance needs to be greater than the tree's total height.
The same page says that where the base of the tree is above or below eye level, extra angles are measured, to the base as well as the top, and added or subtracted. It says that on ground sloping more than 6 degrees (10 percent), slope distance is measured. This calculator covers level ground only.
The GLOBE Program's tree height field guide uses the same formula, with the tangent taken from a table, and says to stand where the angle is as close to 30 degrees as possible and at least as far from the tree as it is tall. Its stand-by-tree guide for sloping ground adds the height of the point on the trunk that is seen at a zero-degree reading.
Arithmetic only. The answer is only as good as the numbers entered. It is not a plan or a safe working load for any job.
Sources
- University of British Columbia, Faculty of Forestry BC BigTree website, Height measurements, read October 8, 2026
- GLOBE Program, field guide Graminoid, Tree and Shrub Height (Biometry Protocol, 2005), read October 8, 2026
- GLOBE Program, field guide Measure Tree Height on a Slope: Stand by Tree Technique (Biometry Protocol, 2005), read October 8, 2026