How to Use the Wheelchair Ramp Slope Calculator
Wheelchair ramp safety is expressed as a slope ratio (1:X) — how much horizontal run is needed for every unit of vertical rise. The ADA (Americans with Disabilities Act) sets a maximum slope of 1:12 for accessible ramps, meaning at least 12 inches of run for every 1 inch of rise. ADA guidelines also cap a single ramp run at a maximum rise of 30 inches before a level landing is required, and a gentler slope of 1:16 to 1:20 is generally recommended for easier, more comfortable use.
Enter the rise (height) and ramp length and this calculator computes the actual slope ratio, checks it against the ADA standard, and shows the minimum ramp length needed to meet the 1:12 requirement. It's a handy reference when planning a ramp or checking an existing one, though a full accessible design also needs to account for handrails, minimum clear width, and landing requirements — consult a licensed contractor for final construction plans.
Frequently Asked Questions
It means the ramp must run at least 12 inches horizontally for every 1 inch of vertical rise. For example, a 6-inch rise requires a ramp at least 6 feet (72 inches) long.
Yes — ADA guidelines limit a single ramp run to a maximum rise of 30 inches before a level landing is required, regardless of the slope ratio.