Ramp Slope Calculator
Calculate ramp slope ratio and percentage. Determine if a ramp meets ADA accessibility standards (1:12 maximum).
Formula & Explanation
The ramp slope calculator determines the steepness of a ramp and whether it meets accessibility standards. **Slope Ratio** = rise : run (e.g., 1:12 means 1 inch of rise per 12 inches of run) **Slope Percentage** = (rise ÷ run) × 100% The ADA (Americans with Disabilities Act) standard for accessibility ramps is a maximum slope of 1:12, or 8.33%. This ensures that wheelchairs and people with mobility limitations can safely navigate the ramp. Steeper ramps (1:8 or 1:10) may be permitted for short runs or in certain situations, but 1:12 is the safest standard. Always verify local building codes and accessibility regulations for your project.
Assumptions
- •The standard ADA ramp slope is 1:12 (8.33% maximum) for public and commercial use
- •Residential ramps may be permitted at steeper slopes (up to 1:8 or 1:10) for shorter runs, subject to local code
- •This calculator assumes a straight ramp; landings and switchbacks require additional geometry
- •Ramp width is typically 36" minimum for wheelchair accessibility (42" preferred); this is not calculated here
- •Handrails are required on ramps (34-38" height, 1.25-2" diameter); verify code requirements separately
- •Snow load, ice, and weather exposure may affect ramp safety and require additional measures
- •Building codes vary by jurisdiction; local AHJ (Authority Having Jurisdiction) approval is required before construction
Example Calculation
A 1:12 slope (1 inch rise per 12 inches run) equals 8.33% and is the ADA standard for accessible ramps. This ratio provides a safe, usable slope for wheelchairs and people with mobility aids.
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