Enter your Vertical Rise and Application Type into the Ramp Calculator to find the Required Ramp Length that meets the right standard — plus your Slope Ratio, Slope Angle, and Slope Percentage so you have the full picture before you build.
Required Ramp Length
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Slope Ratio
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Slope Angle
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Slope Percentage
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Ramp slope is calculated as rise over run. For a 1:12 slope (ADA standard), you need 12 inches of ramp length for every 1 inch of vertical rise. The slope can be expressed as a ratio, percentage, or angle in degrees.
The ADA standard slope for wheelchair ramps is 1:12, meaning 1 inch of rise for every 12 inches of horizontal run. This equals approximately 4.8 degrees or 8.33% grade, providing safe access for wheelchair users.
ADA allows a maximum slope of 1:12 for new construction. Gentler slopes like 1:16 or 1:20 are more comfortable. Steeper slopes up to 2:12 may be acceptable for residential use with assistance, while 3:12 is only suitable for unoccupied loading.
ADA-compliant ramps must have a maximum slope of 1:12, minimum width of 36 inches, landings every 30 feet, handrails on both sides, and edge protection. The surface must be stable, firm, and slip-resistant with proper drainage.
Commercial ramps must meet strict ADA guidelines with 1:12 maximum slope. Residential ramps have more flexibility, allowing steeper slopes like 2:12 when users have assistance, though gentler slopes are always preferable for safety.
For a 12-inch rise: ADA standard (1:12) requires 12 feet, comfortable slope (1:16) needs 16 feet, gentle slope (1:20) requires 20 feet. Residential occupied can use 6 feet, while loading ramps may use 4 feet.
A 100% slope equals a 45-degree angle, meaning the rise equals the run (1:1 ratio). This is extremely steep and not suitable for wheelchair access. Safe wheelchair ramps typically range from 2.4% to 8.33% grade.