What Is the ADA Ramp Calculator?
A wheelchair ramp is not a stair laid flat; it is a precision slope where a few inches of error decide whether a wheelchair user can climb it independently or not at all. The ADA Standards for Accessible Design, section 405, control every dimension: the running slope, the cross slope, the landings, the handrails, the edge protection, and the surface. This free ADA ramp calculator checks your design against all of them from a single input, the total rise the ramp must overcome. It works out the minimum run length at the 1:12 maximum slope, tells you where intermediate landings are required, sizes the top, bottom, and turn landings, and verifies handrail height, extensions, and edge protection. Designing to the absolute maximums is legal but rarely good: a ramp built exactly at 1:12 with no construction tolerance and no rest landings is exhausting to use, so the calculator's steps below push you toward the gentler, more forgiving layout wherever your site allows it. Whether you are adding an accessible entrance to a business, a church, or a home, running the numbers here first is far cheaper than rebuilding a non-compliant ramp after an inspection or a complaint.
How to Use This Calculator
- Enter the total rise, the vertical height the ramp must overcome, from the lower walking surface to the upper one. Measure finished surface to finished surface.
- Read the minimum run length at the 1:12 maximum slope (8.33 percent). That is one foot of ramp for every inch of rise, so a 24 inch rise needs at least 24 feet of ramp before landings. If your site allows it, choose a gentler slope; the calculator shows both.
- Check the single-run rise limit. No single ramp run may rise more than 30 inches, so any ramp climbing higher must be broken into multiple runs with intermediate landings between them.
- Size the landings. Top and bottom landings must be at least 60 inches long and at least as wide as the ramp. Any landing where the ramp changes direction must be at least 60 by 60 inches so a wheelchair can turn.
- Verify handrails. Any ramp with a rise greater than 6 inches needs handrails on both sides, 34 to 38 inches high, continuous along the full run, with 12 inch horizontal extensions beyond the top and bottom of the ramp.
