Wheelchair Ramp Length Calculator

About this calculator

This calculator finds the ramp run needed for a given rise using the ADA-recommended maximum slope of 1:12 — meaning 1 inch of vertical rise requires at least 12 inches of horizontal ramp length — drawn from the Americans with Disabilities Act Standards for Accessible Design (and mirrored in the ICC A117.1 accessibility code). A gentler custom ratio can also be used, since 1:12 is the maximum allowed slope, not necessarily the most comfortable one; many accessibility guides recommend 1:16 to 1:20 where space allows.

Contractors and accessibility consultants use this to size compliant ramps for building entrances and public facilities, and homeowners installing a ramp for a wheelchair or mobility scooter over a step or threshold use it to figure out, before buying materials, how much horizontal space the ramp will actually take up.