By Zencalcy Editorial TeamLast reviewed About us
Grade is rise over run, expressed as a percentage; the same slope in degrees is atan(rise ÷ run). Site work mixes the two — drainage plans in percent, ramps and pipe in degrees — so being able to move between them matters.
Slope, grade and elevation change from rise and run.
grade % = rise ÷ run × 100 angle = atan(rise ÷ run)
A 2% grade is about 1.15°, and 100% is 45°. A pipe needs 1–2% for drainage; a driveway should stay under 15%; ADA ramps max out at 8.33%.
| Symbol | Meaning |
|---|---|
| rise | Vertical change. |
| run | Horizontal distance. |
| g | Grade in percent. |
Grade is 3.0%, the angle 1.72°, and the elevation changes 0.6 ft over 20 ft.
Continue with the Angle Cut Calculator, Angle of Depression Calculator, Bolt Circle Calculator, or the Bowl Segment Calculator — or browse more layout & geometry and all construction calculators.
Degrees = atan(percent ÷ 100). A 10% grade is 5.71°.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026