Grade is how steep a slope is between two points, and it shows up everywhere in site work — drainage swales, driveways, roads, and retaining walls. This guide explains how to turn a simple rise and run into the grade percentage, angle, and ratio that different codes and drawings expect.
How the Elevation Grade Calculator works
Grade percentage is the rise (vertical elevation change) divided by the run (horizontal distance), multiplied by 100. The same ratio converts to an angle in degrees using the arctangent function, and to a run:rise ratio (like 4:1) by simply dividing run by rise. All three describe the exact same slope — they are just different notations preferred by different trades and codes. Rise and run must be entered in the same unit (feet, inches, or meters); the unit itself cancels out of the math, since grade is a ratio.
Inputs and what they mean
Rise is the vertical elevation change between your two points — positive for uphill, negative for downhill. Run is the horizontal distance between the same two points, and it must be nonzero (a zero run is a vertical drop, which has no defined grade). The unit selector (feet, inches, meters) is for labeling only; as long as rise and run use the same unit, the resulting percentage, angle, and ratio are unaffected.
Limits and edge cases
This calculator gives you the geometric grade only — it does not check drainage codes, driveway ordinances, or ADA/accessibility slope limits, all of which vary by jurisdiction and application. A near-zero grade (under about 1%) often does not drain well in practice, and a very steep grade (above roughly 20%) frequently exceeds residential driveway codes or needs retaining walls, switchbacks, or an engineered design. Always confirm site-specific requirements with your local building department or a civil engineer before construction.