Ramp Slope Calculator
For a given rise and slope ratio, find the run length you need, the actual ramp length to build or buy, and the slope in percent and degrees.
Your results
Worked example
A porch step with a rise of 60 cm, at a 1:12 ratio:
- Run: 60 cm × 12 = 720 cm = 7.20 m of horizontal distance
- Ramp length: √(720² + 60²) = √522,000 = 722.5 cm = 7.22 m
- Slope: 1 ÷ 12 × 100 = 8.33%, an angle of 4.76°
Notice how much ground a code-style ramp takes: a single 60 cm step needs over 7 metres of run. Higher rises are usually handled with switchbacks and level landings, which this calculator does not lay out.
How this calculator works
The ratio describes how many units of horizontal run you get for each unit of rise. A 1:12 ramp climbs 1 cm for every 12 cm of run. Gentler ratios (1:16, 1:20) are noticeably easier for a person pushing their own wheelchair, and are often preferred where space allows, even when 1:12 is permitted.
Common questions
Which ratio does the building code require?
It varies by province, municipality, and whether the building is a house or a public building. Many Canadian accessibility standards use 1:12 as the maximum slope for a barrier-free ramp, with limits on run length before a level landing is required, plus rules for handrails, width, and cross slope that this calculator does not cover. Treat the output as planning math only and verify the current requirements with your local building department or accessibility code before building anything intended for public or required accessible use.
What ratio should I use for a home ramp, a shed ramp, or a trailer ramp?
For a home wheelchair ramp, 1:12 is the steepest commonly accepted, and 1:16 or 1:20 feels far better in daily use. For loading ramps (mowers, ATVs, moving), much steeper slopes are normal, often around 1:4 to 1:6, but the equipment maker's guidance governs. Enter a custom ratio to work those out.
Guideline only. This calculator does slope geometry only. It does not account for landings, handrails, edge protection, width, cross slope, surface, or structural requirements. Accessibility and building code requirements vary by jurisdiction and change over time: verify local accessibility code and building code requirements with your municipality before designing or building a ramp for accessible use. Mississippi Maple accepts no liability for decisions made using this calculator.