Figuring Out the Percent Grade of A Climb

You always hear about the percent grade of climbs during the grand tours, or other road races. The final climb up to my house after any road ride is a fairly harsh way to finish up a ride, and I wanted to see what it was.I realized I wasn't truly sure how they determined what the percent grade of a climb was. As it turns out, it's pretty simple, it's just rise over run, or the tangent of the angle. So, you can easily figure out the average gradient of a climb by using Google Maps for quick distance, and Google Earth for the elevations. You don't need addresses in Google Maps, just find the area on the map, and right click to set start and end points. In Google Earth you can just hover over the spot and look at the status info at the bottom to see the altitude (in meters). Using that, I found that the average gradient, over the .7 mile last climb to my house is 9.2%. Not too shabby.Now go figure out the pain of your local climb...