Formula
Gradient % = (Rise / Run) × 100
Angle = arctan(Rise / Run)
Ratio = 1 in (Run / Rise)
5m rise over 100m horizontal:
Gradient = 5% = 1:20 = 2.86°
Frequently Asked Questions
IRC recommends: 3.3% (plain terrain), 5% (rolling), up to 10% (hill roads). Steeper gradients reduce speed and fuel efficiency.
A 100% gradient means the rise equals the run — a 45° angle. It does not mean vertical (which would be infinite %).