Ramp Slope for 3 in Rise over 36 in Run (Door Threshold)
A short door-threshold ramp with a 3-inch rise over a 36-inch run has an 8.3% grade, meeting ADA 1:12 slope 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 slope and grade for a compact door-threshold wheelchair ramp with a 3-inch rise and 3-foot horizontal run.
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.