Ramp slope and grade formulas
slope ratio = horizontal run ÷ risegrade % = rise ÷ run × 100ramp length = √(rise² + run²)A run twelve times the rise produces a 1:12 ratio and an 8.33% grade.
Ramp slope calculator
Convert vertical rise and horizontal run into a 1:X slope ratio, grade percentage, angle, and sloped ramp length.
Enter the ramp rise and run
Rise is the vertical height change. Run is the horizontal distance—not the length measured along the ramp surface.
Geometry is not an accessibility determination
The calculator reports ratio, grade, angle, and sloped length from the dimensions entered. A complete ramp also depends on clear width, landings, rises between landings, handrails, edge protection, surface, cross slope, and the rules that apply to the site.
- Measure vertical rise between finished surfaces.
- Use horizontal run, not ramp-board length, for the ratio.
- Confirm structure, foundations, connections, and local requirements before building.
Check more than slope
Requirements vary with use and jurisdiction. Confirm landings, door maneuvering space, surface, drainage, cross slope, width, handrails, guards, edge protection, structure, and connections before building.