ADA Compliance Ramp and Accessibility Calculator
Calculate ADA-compliant ramp dimensions based on rise height, including required ramp length, slope ratio, landing requirements, and handrail specifications per the ADA Standards for Accessible Design (Section 405).
Total height the ramp must overcome
Minimum ADA requirement: 36 inches clear width
1:12 is the maximum allowed slope per ADA Section 405.2
Minimum ADA requirement: 60 inches square at top and bottom
Formulas Used
Ramp Run Length: Run = Rise × Slope Ratio (e.g., Rise × 12 for 1:12 slope)
Slope Percentage: Slope% = (1 ÷ Slope Ratio) × 100
Slope Angle: θ = arctan(1 ÷ Slope Ratio) × (180 ÷ π)
Number of Runs: Runs = ⌈Rise ÷ 30⌉ (ceiling division; max 30 in rise per run)
Rise per Run: Rise per Run = Total Rise ÷ Number of Runs
Total Horizontal Distance: Total = Run + (Total Landings × 60 in)
Ramp Surface Area: Area = (Run ÷ 12) × (Width ÷ 12) in square feet
Handrail Bottom Extension: Extension = 12 in + Run Length per Segment
Assumptions & References
- ADA Section 405.2: Maximum ramp slope is 1:12 (8.33%). Slopes between 1:16 and 1:20 are preferred where space allows.
- ADA Section 405.5: Minimum clear ramp width is 36 inches between handrails.
- ADA Section 405.6: Maximum rise for any single ramp run is 30 inches. Multiple runs with intermediate landings are required for greater rises.
- ADA Section 405.7: Landings must be at least 60 × 60 inches at the top and bottom of each ramp run and at any change of direction.
- ADA Section 405.3: Cross slope of ramp surfaces must not exceed 1:48 (2.08%).
- ADA Section 405.9: Edge protection (curb, wall, or barrier) of at least 4 inches is required on all non-wall sides of ramp surfaces and landings.
- ADA Section 505.2: Handrails are required on both sides of ramps with a rise greater than 6 inches.
- ADA Section 505.4: Handrail gripping surfaces must be 34–38 inches above the ramp surface.
- ADA Section 505.10: Handrails must extend 12 inches horizontally beyond the top of the ramp and 12 inches plus the ramp run beyond the bottom.
- This calculator is based on the 2010 ADA Standards for Accessible Design published by the U.S. Department of Justice.
- Local building codes may impose stricter requirements. Always verify with a licensed architect or accessibility consultant.
- This tool is for estimation purposes only and does not constitute professional engineering or legal advice.