If you are thinking of building a driveway or replacing one, determining the grade of the slope is an important first step. This number precisely indicates how steep the slope is, providing an easy, common point of reference to use in design considerations. Driveways with steep slopes are unsafe, and your county or municipality may even prohibit building a driveway on ground that is too steep, so you must measure your slope before proceeding.
Drive a stake into the ground with a hammer next to one of the upper corners of the driveway. Put a second stake into the ground at the opposite, bottom corner. This second, lower stake may need to be substantially longer than the first stake to take an accurate measurement.
Tie a string to the upper stake at ground level. Take the string down to the lower stake and tie it into place. Put a string level on the string, and adjust it until it is horizontally level.
Measure the distance between the string at the lower stake and the ground. This measurement is the drop of the slope on your driveway.
Walk down the driveway from end to end with a measuring wheel to determine its length.
Divide the drop of the slope by the length of the driveway to determine grade. A 30-foot (360-inch) driveway with a drop of five inches has a modest grade of 1.38 percent (5/360=0.0138).