Slope & Grade Calculator
Convert between rise/run, grade percent, angle in degrees, and ratio form (1:12 etc.).
How to Use
- Enter any pair of rise/run, or type a grade / angle directly.
- All forms update.
Slope
Classification
Common slopes
Wheelchair ramp (ADA)
≤ 1:12 (8.33%, 4.76°)
Stairs
~30–35° typical (rise/run = 0.75)
Flat roof (min)
1:50 = 2% for drainage
Shingle roof
4:12 min · steep 9:12 or more
Highway grade
4% max on interstates typical
Frequently Asked Questions
ADA-compliant ramps?
Max 1:12 slope (8.33%) — any steeper needs a landing/handrail/etc.
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