Elevation Grade Calculator

Elevation grade describes vertical change relative to horizontal distance. It is widely used for roads, driveways, ramps, drainage runs, landscaping, and site preparation because it communicates steepness in a form that designers and builders can apply. The calculator subtracts the start elevation from the end elevation to find rise, then divides rise by horizontal distance and multiplies by one hundred. A positive result is uphill from start to end, a negative result is downhill, and zero indicates level conditions. Grade percentage and slope angle describe the same geometry in different ways. The angle is the arctangent of rise divided by run, expressed in degrees. A one-hundred-percent grade is therefore not vertical; it represents equal rise and run and corresponds to forty-five degrees. The displayed one-in ratio gives the horizontal run associated with one unit of absolute vertical change. For example, a five-percent grade is a rise of five units per one hundred horizontal units, equivalent to one in twenty. All three measurements must use consistent units. Elevations and distance may be in meters, feet, or another linear unit, but mixing units produces a meaningless result. Horizontal distance means the plan-view run, not the measured distance along an inclined surface. If only slope distance is available, it must be converted using surveying geometry before entering it. Precise work should use elevations from calibrated levels, total stations, or suitable survey equipment rather than rough consumer positioning data. Project requirements vary substantially. Accessible routes, highways, residential streets, parking areas, sanitary piping, and open drainage channels each have distinct maximum or minimum grades. A slope that drains effectively may be unsafe for pedestrians or may create erosion from excessive velocity. Cross slope, vertical curves, transitions, soil stability, surface traction, and local climate can matter just as much as the simple longitudinal grade shown here. Use this calculator to verify field notes, compare alternatives, or communicate a proposed slope. Retain the sign when direction matters, and check whether a specification uses percent, degrees, or a ratio. For construction layout, establish reliable benchmarks and account for tolerances, settlement, pavement thickness, and drainage structures. The arithmetic is exact for the entered geometry, but safe design still requires applicable codes, complete site data, and professional judgment.