Converters & essentials
Slope & Gradient Calculator
Every trade writes slope differently - percent, degrees or 1:x. Enter rise and run once and read all three.
Calculator
Fill in the fields above to see results.
How it works
Gradient percent is rise divided by run times 100. The angle is the arctangent of rise over run, and the ratio is 1 : run/rise - the format drainage and ramp regulations use.
Frequently asked questions
What is a 1:40 gradient in percent and degrees?
1:40 means 1 unit of fall per 40 along - 2.5% or about 1.4 degrees. Typical foul drainage for 100 mm pipes runs between 1:40 and 1:80.
What gradient can a wheelchair ramp be?
ADA (US) and UK Part M both cap ramps at 1:12 (8.3%), with gentler slopes preferred - see the dedicated ramp calculator for lengths and landings.