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Elevation Grade Calculator.

Calculate grade percentage, angle, and slope length.

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01

Set your values

Results update as you type.

rise: 3

rise

3.000
run: 4

run

4.000
Grade: 75

Grade

75.000
Angle: 36.87

Angle

36.870
Slope length: 5

Slope length

5.000

Use Cases

Road and driveway design

Determine the steepness of a road or driveway to ensure it meets safety and accessibility standards. Use the grade percentage to assess drainage and vehicle traction.

Example: A driveway with a rise of 2 feet over a run of 20 feet has a 10% grade.

Landscaping and drainage planning

Calculate the slope of terrain for proper water runoff and to design retaining walls or terraces. The angle helps in planning erosion control measures.

Example: A garden slope with a rise of 1.5 meters over a run of 6 meters has a 25% grade.

Frequently Asked Questions

How do I calculate elevation grade percentage?
Enter the vertical rise and horizontal run in any consistent units. The calculator divides rise by run and multiplies by 100 to give the grade percentage. For example, a rise of 3 units over a run of 12 units yields a 25% grade.
What is the angle of the slope?
The angle is the arctangent of the rise divided by the run. It is expressed in degrees. For instance, a 1:1 slope (rise equals run) corresponds to a 45-degree angle.
How is slope length calculated?
Slope length is the hypotenuse of a right triangle formed by rise and run. It is computed using the Pythagorean theorem: square root of (rise² + run²). This gives the actual distance along the slope.

Tips & Common Mistakes

Tips

  • Ensure rise and run are in the same units (e.g., both feet or both meters) before entering them.
  • For accurate results, measure the horizontal run, not the slope distance, when determining grade percentage.
  • Use the slope length output for estimating material quantities like paving or fencing along the incline.
  • Remember that a grade of 100% corresponds to a 45-degree angle, not vertical.

Common Mistakes to Avoid

  • Mixing units, such as entering rise in feet and run in meters, which leads to incorrect calculations.
  • Confusing slope length with horizontal run when measuring on the ground; always measure the horizontal distance for run.
  • Assuming a grade percentage equals the angle in degrees; they are different (e.g., 100% grade = 45°).

Last updated: August 13, 2026