Ramp Slope Calculator

in
in
Construction

Calculate ramp slope, angle, run length, and ADA compliance for wheelchair ramps.

Formula

Slope% = rise/run × 100; Angle = atan(rise/run); ADA max: 1:12 (8.33%)
  • ADA Standard §4.8.2: Maximum slope for wheelchair ramps = 1:12 (8.33%).
  • For every 1 inch of rise, you need a minimum 12 inches of run.
  • Maximum rise per ramp run: 30 in before a required landing.
  • Minimum clear width: 36 in (ADA).

12 in rise, 144 in run

Inputs
  • Rise (height): 12 in
  • Run (horizontal distance): 144 in

Slope = 12/144 = 8.33%. Angle = 4.76°. Ratio = 1:12. ADA compliant.

Frequently asked questions

What is the ADA maximum ramp slope?
ADA §4.8.2 allows a maximum slope of 1:12 (8.33%). Steeper slopes are only permitted for existing buildings with space constraints — maximum 1:10 or 1:8 in limited cases.