How it works
Calculate slope percentage and angle from rise and horizontal run in the same unit. Material rules and local codes are not evaluated.
pitch = rise/run; angle = atan(pitch)
Worked example
Show example inputs and result
Vertical rise: 1.5 · Horizontal run: 4.
- Slope
- 37.5 %
- Angle
- 20.55604522 °
Questions and answers
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Method reviewed: October 8, 2026 · Methods & accuracy