The grade of a driveway refers to how steeply it changes elevation. When planning to redo your driveway, you may want to make sure you keep the same slope. Many driveways slope to prevent water from pooling on the driveway. To calculate the grade of a driveway, you need to know the driveway length and the change in elevation.
Measure the change in elevation for the driveway using a string. Have one assistant hold the string on the ground at the top of the driveway and another stand at the bottom and hold the string so it is level. Measure the distance the string is from the ground at the bottom of the driveway to find the change in elevation.
Find the length of the driveway by measuring the length of the string used in Step 1.
Divide the rise of the driveway by the length of the driveway to find the grade. For example, if the driveway rises 2 feet over 20 feet divide 2 by 20 to get 0.2, or 20 per cent, as the grade.