How the calculation works
The formulas
All three modes use an entered horizontal run to establish scale. A flat slope is allowed; negative rises and angles of 90° or more are rejected. Sloped length is the hypotenuse, not the horizontal run.
Gradient% = rise ÷ horizontal run × 100
Angle = atan(rise ÷ horizontal run)
Sloped length = √(rise² + horizontal run²)
Ratio = 1 : (horizontal run ÷ rise)
Assumptions to check
- Ratios are displayed as 1 vertical : N horizontal. A level slope is labelled level instead of dividing by zero.
- The output does not establish a compliant ramp, drainage fall, or safe excavation slope.
A worked example
A 0.5 m rise over 5 m horizontal run is 10%, approximately 5.7106°, a 1:10 ratio, and 5.0249 m sloped length.