Elevation Grade Calculator
Find the slope of any surface by entering the vertical rise and horizontal run. Get grade percentage, angle in degrees, slope ratio, and slope length for construction, landscaping, or road projects.
Vertical elevation change in feet or meters
Horizontal distance over which the rise occurs
What is elevation grade and how is it calculated?
Elevation grade (or slope) measures the steepness of a surface. It is calculated as the vertical rise divided by the horizontal run, expressed as a percentage. Grade % = (Rise ÷ Run) × 100. For example, a 10-foot rise over 100 feet of horizontal distance equals a 10% grade. Grade is also expressed as a ratio (1:10) or as an angle in degrees from horizontal.
What is the difference between grade percentage and degrees?
Grade percentage is the rise divided by run times 100, while degrees measure the angle from horizontal. A 100% grade equals a 45-degree angle. The conversion: Degrees = arctan(Rise ÷ Run) × (180 ÷ π). A 10% grade equals about 5.7 degrees, 20% equals 11.3 degrees, and 50% equals 26.6 degrees. For most construction applications, grade percentage is preferred.
What are acceptable grade percentages for different applications?
Acceptable grades vary by use: Roads: maximum 6-8% for highways (15% for local roads). Driveways: maximum 12-15% (steeper may cause scraping). Walkways: 2-5% slope for drainage, maximum 8.3% for ADA compliance. Lawns: 2-3% minimum away from foundations for drainage. Railroad tracks: maximum 2-3%. Pipes/drainage: minimum 0.25-1% for flow. Athletic fields: 1-2% crown for drainage.
How do I calculate the length of a slope from grade?
The slope length (hypotenuse) is calculated using the Pythagorean theorem: Slope Length = √(Rise² + Run²). For a 10% grade with 10 ft rise and 100 ft run: Slope Length = √(100 + 10,000) = √10,100 = 100.5 ft. The slope length is always slightly longer than the horizontal run. This is important for calculating roofing materials, road paving quantities, and pipe lengths.