What is Elevation Grade?
Elevation grade (also called slope) describes how steep a surface is — a road, driveway, ramp, or drainage pipe — by comparing vertical rise to horizontal run.
The Formula
Grade % = (Rise ÷ Run) × 100. For example, a rise of 3 feet over a run of 100 feet is a 3% grade. This calculator also converts that into an angle in degrees using the arctangent of rise over run, and into a slope ratio (like 33:1), which is another common way slopes are expressed in construction drawings.
- ADA-compliant ramps: generally 8.3% (1:12) maximum
- Typical driveways: under 15-20% is common practice
- Wheelchair-accessible routes: often limited to 5% or less
This calculator is for general planning and educational purposes — always confirm slope requirements against applicable building codes, accessibility standards, and site-specific drainage needs.
Last reviewed August 2026