Ramp Slope Calculator - ADA Compliance & Angle

How to use this tool

1. Enter the rise (vertical height) and run (horizontal length).
2. Read slope ratio, percentage, and angle in degrees.
3. See whether the ramp meets ADA guidelines.

ADA ramp requirements

The Americans with Disabilities Act (ADA) requires accessible ramps to have a maximum slope of 1:12 - 1 inch of rise for every 12 inches (1 foot) of horizontal run. A 30" rise requires at least a 30-foot ramp.

Slope vs. grade

Landing requirements

The ADA requires a level landing (max 2% cross-slope in any direction) at the top and bottom of every ramp run. For long ramps, a landing is also required at least every 30 feet of horizontal run. Landings must be at least 60 × 60 inches to allow wheelchair users to rest and reposition.

Handrail requirements

ADA requires handrails on both sides of a ramp when the rise exceeds 6 inches. Handrail height must be 34–38 inches above the ramp surface. Handrails must extend horizontally at least 12 inches beyond the top and bottom of the ramp. Gripping surfaces must have a cross-section diameter of 1.25–2 inches.

Ramp materials

• Concrete: most durable and permanent; must be broom-finished or have an exposed aggregate surface for slip resistance; expensive to modify after installation.
• Aluminum (modular systems): lightweight, portable, corrosion-resistant; most wheelchair accessibility ramps for doorways are aluminum; slip-resistant surface is typically punched or ribbed.
• Pressure-treated wood: lower cost; must be covered with non-slip strips or paint; requires regular maintenance and resealing.

Vehicle ramps

• Driveway approach: standard vehicle clearance requires ≤10–14° (18–25% grade) for most passenger cars; sports cars and low-profile vehicles may require ≤7°.
• Loading dock approach: max 10% grade (1:10) is recommended for forklift and pallet jack safe operation.
• Trailer ramps for vehicles: vehicle ground clearance determines safe ramp angle; a typical car transporter ramp is 6–8°.