Wheelchair ramp slope calculator (ADA)
Enter the height the ramp has to climb and this returns the minimum ramp length at the ADA's 1:12 maximum slope, plus how many runs and level landings the rise requires. Built from the 2010 ADA Standards.
24.0 ft
Ramp run (min, at 1:12)
- Ramp run (min)
- 288 in
- Ramp runs (30 in rise max each)
- 1 runs
- Level landings
- 0 landings
What this assumes
- Ramp run = 24 in rise × 12 (1:12 max slope) = 288 in = 24.0 ft.
- Runs = ceil(24 in ÷ 30 in max rise per run) = 1; level landings between runs = 0.
- 1:12 is the steepest the ADA allows; a gentler slope (e.g. 1:16 or 1:20) is easier to use and needs more length.
Coverage rates & sources
Every number this calculator uses is a published engineering constant — not an estimate we made up. Here is exactly what it assumes and where each value comes from.
- Max running slope: 1:12 (1 in rise per 12 in run)Source: 2010 ADA Standards for Accessible Design §405.2 — ramp slope
- Max rise per run: 30 inSource: 2010 ADA Standards for Accessible Design §405.6 — rise
- Min clear width: 36 inSource: 2010 ADA Standards for Accessible Design §405.5 — clear width
Before you buy
- 1:12 is the ADA maximum slope; many people find 1:16 to 1:20 far easier — a gentler ramp simply needs more length and is always allowed.
- Any run over 30 in of rise needs an intermediate level landing (≥ 60 in long), and ramps need 36 in minimum clear width plus a level landing top and bottom (§405.7).
- Residential and IRC requirements can differ from the ADA — confirm slope, width, handrail, and landing rules with your local building department.
This is a planning estimate, not a substitute for a pro's on-site measurement. For load-bearing, structural, or code-regulated work, confirm quantities with a licensed contractor.
Frequently asked
What slope is ADA compliant for a ramp?
The 2010 ADA Standards (§405.2) cap a ramp's running slope at 1:12 — about 4.8 degrees. Cross slope is limited to 1:48, single runs to 30 inches of rise, and clear width to a 36-inch minimum.
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