The road grade or gradient is the percent incline of the road. If the road rises one foot for every ten feet of horizontal distance traveled, the road grade is ten percent. Use 0 for a level road. Use a positive number for an uphill grade and a negative number for a downhill grade.
Angle times 1.111111 = percent grade
1 degree = 1.11%
5 degrees = 5.55%
10 degrees = 11.11%
45 degrees = 50%
90 degrees = 100%