Grade / Gradient Calculator
Enter the rise (vertical change) and run (horizontal distance) to calculate the grade as a percentage, angle, and ratio.
Last updated: September 5, 2026
Frequently asked questions
How do I calculate grade as a percentage?
Divide the rise (vertical change) by the run (horizontal distance), then multiply by 100. A road that climbs 6 feet over a 100-foot horizontal distance has a 6% grade (6 ÷ 100 × 100 = 6%).
What's the difference between grade (percentage) and angle (degrees)?
Grade and angle both describe steepness, but grade is rise ÷ run as a percentage, while angle is the arctangent of that same ratio in degrees - a 100% grade is a 45° angle (not 90°, a common misconception), since 100% grade means rise equals run.
What's a typical maximum grade for roads or wheelchair ramps?
US highways are typically limited to about 6-8% grade, residential driveways often go up to 15-20%, and ADA-compliant wheelchair ramps are limited to about 8.3% (1:12) - though exact limits depend on the specific code or standard that applies to your situation.
How do I convert a percentage grade into a ratio like '1:12'?
Divide 100 by the percentage: for an 8.33% grade, 100/8.33 ≈ 12, giving a ratio of 1:12 (1 unit of rise for every 12 units of run) - a format commonly used for ramp and stair codes.
Can grade percentage exceed 100%?
Yes - unlike a percentage of a whole, grade percentage is simply rise divided by run and has no upper cap. A grade over 100% means the rise is greater than the run, corresponding to an angle steeper than 45°.
Does a negative rise value make sense in this calculator?
Yes - a negative rise represents a downhill slope (descending), and the calculator will return a negative grade percentage and angle, mirroring the same magnitude as the equivalent uphill grade but in the opposite direction.