Wheelchair Ramp Calculator

Ramp Run Length is Rise multiplied by Slope Ratio, divided by 12 to convert inches to feet -- a pure product, so Rise and Slope Ratio move the run length by identical proportions and neither one structurally outranks the other. The ADA's own maximum slope is 1:12 (§405.2), the default here. Landing Every (ft) never enters the run-length calculation at all; it only determines how many intermediate landings are inserted along a run that has already been fixed by Rise and Slope Ratio. The ADA Standards actually cap ramp runs by rise, not by run length: §405.6 limits any single run to 30 inches of rise before a landing is required -- at the code-maximum 1:12 slope that 30-inch rise works out to exactly 30 feet of horizontal run, which is why this calculator's default Landing Every (ft) is 30.

Landings Required always includes a top and bottom landing (the "+2" floor, each landing at least 60 inches long per §405.7.3); beyond that, the run is divided into segments no longer than Landing Every (ft), and every additional segment beyond the first needs an intermediate landing. Total Handrail Length is where Rise does double duty: below 6 inches of Rise, §405.8 does not require handrails and the length is zero; the instant Rise exceeds 6 inches, both sides of the ramp need continuous handrail running the full ramp length plus a 12-inch extension at each end per §505.10.1. That 6-inch line is a real on/off switch in the formula, not a rounding artifact -- a ramp at 5.9" of rise needs no handrail at all, while one at 6.1" needs roughly the full run doubled.