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Answer

What is the ADA ramp slope?

1:12 at most: 1 in of rise for every 12 in of ramp, an 8.33% grade (2010 ADA Standards, 405.2). No run may rise more than 30 in before a level landing.

By the Toolkit Cove team · Checked 20 October 2026 · How we calculate

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Side view of a ramp from the ground up to a porch, with a level landing at the bottom, handrails and the rise and run measuredRun = rise × 12Rise60 inlandingHandrails 34–38 in highboth sides, if the rise is over 6 in1 : 12
ADA ramps: slope no steeper than 1:12 (1 in of rise per foot of run), at most 30 in of rise per run, a level landing 60 in long at the top and bottom of every run, and 36 in clear between handrails (405).

Slopes compared

Ramp length per inch of rise
SlopeGradeRamp per inch of rise
1:128.33%12 in (1 ft)
1:166.25%16 in
1:205%20 in

Steeper in tight spots

In existing buildings where space is short, the Standards allow 1:10 for a rise of 6 in at most, or 1:8 for 3 in at most.

More questions

What cross slope is allowed?

1:48 at most, side to side.

Is gentler better?

Usually: the Access Board’s guide recommends 7.5% at most outdoors. It costs length: a gentler ramp is longer.

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