Gradient and fall calculator
Convert fall over a length into a 1-in-X ratio, a percentage and degrees, for paths, drains and ramps.
Drainage and accessibility gradients are set by codes and standards. Confirm the requirement for your job with a plumber or certifier.
How this calculator works
Gradient 1 in X = length ÷ fall (in the same units). Percentage = fall ÷ length × 100. Angle = arctan(fall ÷ length).
Worked example: 50 mm of fall over 5 m is 1 in 100, or 1%, or 0.57°. A 1-in-14 ramp is a 7.1% slope.
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