Surveying & site
Accessibility Ramp Calculator
Ramp length is rise times the gradient ratio - and past 760 mm of rise, regulations split it into runs with level landings.
Calculator
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How it works
At the steepest permitted 1:12, every 10 mm of rise needs 120 mm of ramp. Both ADA (US) and UK Part M cap a single run at about 760 mm of rise, then require a level landing.
Frequently asked questions
What is the maximum wheelchair ramp slope?
1:12 in both the US (ADA) and UK (Part M) for short rises - and both prefer gentler. 1:15 or 1:20 is markedly easier for self-propelled users.
How long a ramp for a 150 mm step?
1.8 m at 1:12, 2.25 m at 1:15, 3 m at 1:20 - plus a level landing at the top and bottom. This tool does the arithmetic for any rise.