Ramp Slope for 4 in Rise over 48 in Run
A ramp with a 4-inch rise and 48-inch horizontal run has an 8.3% grade, meeting ADA 1:12 requirements.
How to use this tool
- Enter the rise (vertical height) and run (horizontal distance) in inches.
- The calculator outputs the slope ratio (e.g. 1:12), grade percentage, and actual ramp surface length.
- ADA-compliant ramps must not exceed 1:12 slope (8.33% grade).
Calculate the percent grade and slope angle for a ramp that rises 4 inches over a 48-inch (4-foot) horizontal distance.
Frequently asked questions
- What is the ADA ramp slope requirement?
- ADA requires a maximum slope of 1:12 (one inch of rise for every 12 inches of run), which equals an 8.33% grade.
- How do I calculate ramp grade percentage?
- Divide the rise by the run, then multiply by 100. For example, a 6-inch rise over a 72-inch run is 6/72×100 = 8.33% grade.