Tree Height Measurement Calculator

Estimate tree height from horizontal distance and sight angles to the top and base.

Inputs

Preset: 30 ft tree sight line

A 30 ft horizontal observation distance, 45° angle to the top and −5° to the base. Measure both signed angles from the same horizontal reference.

Length - Horizontal distance (ft), Top angle (°), Base angle (°)
Enter horizontal distance in ft.
Measure the angle from the horizontal.
Measure the angle from the horizontal.
Formula, inputs and conditions

Formula: Horizontal distance*(tan(Top angle*pi/180)-tan(Base angle*pi/180))

Decimal results are displayed to two places when needed.

Inputs
Horizontal distance and top/base sight angles.
Outputs
Tree height in feet.
Conditions and scope
Distance must be horizontal and the trunk approximately vertical. The estimate does not assess fall risk or pruning safety. Results are planning estimates, not engineering, permit, code or contractor-price decisions.

Use two sight angles from one observation point

Tree height can be estimated from a horizontal distance and angles to the top and base. Keeping both angles signed allows the base to lie above or below the observer’s horizontal reference. Distance must be horizontal, not the length along a sloping ground surface.

Measure and calculate

  1. Measure horizontal distance to the tree’s vertical reference line.
  2. From the same observation point, measure signed angles to the top and base.
  3. Enter degrees between −90° and 90° and inspect whether the geometry matches the tree being measured.
Calculation method

Height = horizontal distance × (tangent(top angle) − tangent(base angle)).

A worked example

Inputs
The observation distance is 30 ft, the top angle is 45° and the base angle is −5°.
Calculation
30 × (tan(45°) − tan(−5°)) = 32.6247 ft.
Result
32.62 ft

The displayed height is 32.62 ft. A leaning trunk, unclear top or imprecise distance can limit the estimate; the formula assumes the sighted top and base share the intended vertical reference.

Read the result

Output interpretation and next steps
Output or checkWhat it means for your project
Estimated vertical height: ftThe result is the difference between two elevations derived from signed sight angles at one observation point.
Measurement geometryUse horizontal distance to the intended vertical reference. Do not add eye height again; unclear top position or a leaning tree can invalidate the simple geometry.

Common questions

Why is the base angle negative?

A base below your horizontal sight line is entered as a negative angle. Subtracting its negative tangent adds the height below that line.

Should I add eye height separately?

Not when both top and base angles are measured from the same observation point in this model. The angle difference already accounts for their vertical separation.