Wheelchair Ramp Length Calculator: How Long a Ramp for Your Step?
A ramp has to be long enough for the height of the step. The ADA Standards set the limit at a slope of 1:12, which means 12 inches of ramp for every 1 inch of rise. Enter your step height below and the calculator gives the length that slope needs, plus the portable ramps in our guide that are long enough.
How the Calculation Works
The ADA Standards say a ramp run should have a running slope not steeper than 1:12. That means the ramp length in inches is the rise in inches times 12. A 2-inch step needs 24 inches, a 3-inch step 36 inches, a 6-inch step 72 inches and an 8-inch step 96 inches.
In an existing site where space is limited, the ADA allows steeper slopes, up to 1:8, but only for small rises. A slope steeper than 1:12 up to 1:10 is allowed for a rise of 6 inches or less, and a slope steeper than 1:10 up to 1:8 for a rise of 3 inches or less. Anything steeper than 1:8 is prohibited.
Other ADA Ramp Numbers
- Rise: 30 inches at most for one run.
- Clear width: 36 inches minimum. Portable ramps in our guide are about 29 inches wide.
- Landings: 60 inches long at the top and bottom, and 60 by 60 inches where the ramp turns.
- Handrails: required on ramp runs with a rise over 6 inches.
- Edges: edge protection on both sides.
The ADA covers public and commercial buildings. A private home does not have to follow it, but the 1:12 rule is the clearest published guide to a slope a chair user and a helper can manage. The listings for portable ramps say they work at steeper slopes, so use this calculator to choose the length, not the listing's step height range.
Ramp Length Questions
How Long a Ramp Do I Need for a 4-Inch Step?
48 inches, or 4 feet, at 1:12. Our guide's 3-foot ramps are too short for 4 inches at that slope, and the 6-foot ramp is longer than needed.
Can I Use a Shorter Ramp?
The ADA allows steeper slopes only for small rises in existing sites, and prohibits anything steeper than 1:8. A steeper ramp is harder to push up and easier to tip on.
Do I Need a Handrail?
The ADA asks for handrails on ramp runs with a rise over 6 inches. The portable ramps in our guide have side baffles, not handrails.
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