Ramp Calculator Pro (USA)

The maximum slope for an ADA-compliant wheelchair ramp in new construction is 1:12, which means for every 1 inch of vertical rise, you need 12 inches (1 foot) of horizontal run. This equals approximately 8.33% grade or 4.76 degrees. For existing buildings where space is limited, slopes up to 1:10 (10% grade) are permitted for rises up to 6 inches, and 1:8 (12.5% grade) for rises up to 3 inches only.

To calculate the length of a wheelchair ramp, multiply the vertical rise (height) by the slope ratio. For a standard 1:12 slope, multiply the rise in inches by 12 to get the horizontal run in inches. For example, a 24-inch rise requires a 288-inch (24-foot) horizontal run. The actual ramp length (the slanted surface) will be slightly longer due to the Pythagorean theorem.

The maximum rise for an ADA ramp without an intermediate landing is 30 inches. After 30 inches of rise, a level landing of at least 60 inches (5 feet) in length must be provided. This landing allows wheelchair users to rest before continuing. There is no limit to the total rise of a ramp system as long as intermediate landings are provided every 30 inches of rise.

An ADA-compliant wheelchair ramp must have a minimum clear width of 36 inches between handrails. However, 44 inches is recommended to allow comfortable two-way traffic. If the ramp serves as an accessible route to a doorway, additional width considerations apply. For doorways, the landing must be at least 60 inches deep.

Handrails are required on both sides of ramps when the rise exceeds 6 inches. The handrails must be between 34 and 38 inches above the ramp surface, provide a gripping surface between 1.25 and 2 inches in diameter, extend 12 inches horizontally at the top and bottom, and have at least 1.5 inches of clearance from any wall.

ADA-compliant ramps can be built from concrete, wood (pressure-treated lumber), aluminum (modular systems), steel, or composite materials. The key requirements are: the surface must be firm, stable, and slip-resistant; the ramp must maintain the required slope and dimensions; edge protection must be provided; and the structure must support the expected loads.