Slope Degrees Calculator
Convert a signed percent grade or measured rise and horizontal run into slope angle in degrees, with clear distance and direction conventions.
Convert a percent grade into the angle an incline makes with the horizontal. You can also enter a measured rise and horizontal run, useful when checking a profile drawing or comparing a slope description with an angle measurement.
How to use this tool
- Choose percent grade or rise and run as your available measurements.
- Enter a positive value for ascent or a negative value for descent in your chosen direction.
- For measured distances, use the same metre or foot unit and enter a strictly positive horizontal run.
- Read the angle in degrees and the equivalent signed grade.
Formula
angle = atan(grade / 100); grade = 100 × rise / horizontal run
The inverse tangent gives an angle between −90° and 90°. The displayed result is converted from radians to degrees. Run is the horizontal projection; substituting the diagonal surface distance changes the calculation. A vertical face has zero horizontal run and is outside this finite-grade model.
Example
A rise of 1,000 ft over 2,000 ft horizontally has a grade of 50%. Its angle is atan(0.5), or 26.565051°. Equal rise and horizontal run instead give 100% grade and 45°.
Frequently asked questions
Is 10% grade the same as 10 degrees?
No. Ten percent means 10 units of rise per 100 horizontal units; its angle is about 5.710593°. Angle and percent have different scales.
Why can grade exceed 100%?
It exceeds 100% when the rise is larger than the horizontal run. That is steeper than 45°, while still short of vertical.
Does changing metres to feet change the angle?
No, provided both distances use the same unit. Their ratio is unchanged. The selector labels the measurements; it does not reinterpret a foot value as a metre value.
Sources
Last updated: 2026-10-30