How is it measured on site?

With a clinometer, an inclinometer app, or a level and a protractor. Measure from eye height and add it to the height above the ground.

What if the ground is not level?

Use the difference in elevation between the observer and the target, and measure the horizontal distance, not the slope distance.

Angle of Depression Calculator

By Zencalcy Editorial TeamLast reviewed September 2026About us

The angle of depression is measured downward from horizontal, from the observer to the target. Because alternate angles are equal, it is the same as the angle of elevation from the target back to the observer — a useful check when you are the one holding the level.

Angle of Depression Calculator

Angle below horizontal to a point you can see.

Configuration

Height above target (ft)
Horizontal distance (ft)

Enter values and calculate

How to use this calculator

Enter the observer's eye height above the target.
Enter the horizontal distance to the target.
Read the angle of depression, line-of-sight distance and slope.

Formula

θ = atan(height ÷ distance)

The target is assumed to be at the same elevation as the base of the height measurement. For a target on a hill, use the elevation difference rather than the observer's height alone.

Symbol	Meaning
h	Vertical drop to the target.
d	Horizontal distance.
θ	Angle below horizontal.

Worked example

Example: 30 ft up, 50 ft away

atan(30 ÷ 50) = 30.96° below horizontal, and the line of sight is 58.3 ft.

Continue with the Angle Cut Calculator, Bolt Circle Calculator, Bowl Segment Calculator, or the Countersink Depth Calculator — or browse more layout & geometry and all construction calculators.

Angle of Depression Calculator FAQ

No. It is defined as downward from horizontal, so it is between 0° and 90°.

Sources & methodology

Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.

Reference material used to build and check this calculator: