I-Home improvement

[WTMHouston]

This probably a question that someone will answer and I will say, Duh, but here goes anyway. I am looking for a tool that I can lay on a surface and measure the angle of incline of that surface. Specifically, I am looking for the angle of incline of a section of a parking lot driveway. I know that if I knew the total rise in elevation over the given distance that I could figure it out mathematically, but I have no easy way (that I can see) of finding or measuring the total rise in elevation over the distance, which I do know or can easily measure. Thanks in advance to any or all who may have what is probably an easy answer.