I just hold a protractor up to the side of the surface. Measuring in degrees, is the way to go. When inches (or cm) are used, the size of the surface has an impact on what is actually going on.

Central has them as does Don's Hobbies.

As for personal taste, after the first filght or two, I toss the measuring devices away. I adjust the throw based on how I like the plane to fly. I end up with a low rate that is fairly aggressive, but still stable enough (no elevator snaps or the like). High rate is all I can get.