Maker & Reference
Grade / Slope Calculator
Grade = rise / run × 100. Convert between %, degrees, and ratio (e.g. 4:1). Critical for road design, drainage, ADA ramps.
Grade %
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- Degrees
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- Ratio
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- Use case
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FAQ
ADA ramp max? +
1:12 (8.33%) maximum. Maximum total rise on a single run is 30". Then required level landing.
Drainage minimums? +
Concrete: 1% min. Paved: 0.5-1%. Lawn: 2%+. Below 0.5% and water will not flow reliably.