A comprehensive educational community devoted to trim carpentry, finish carpentry and architectural millwork. Hosted by nationally recognized author and finish carpentry specialist Gary M. Katz.
  understanding mitersaw angles  
The angle scale on most mitersaws isn't user friendly for many carpenters because you can't match the numbers on a protractor to the angles on the mitersaw scale.  That's because an engineer designed the scale and not a carpenter, so we all say "Hey, cut that one at a 22 1/2!" when the angle is really 67 1/2°.
The degrees at the top of the illustrated scale are the ones found on most mitersaws.  The degrees at the bottom of the illustrated scale are the acutal degrees that correspond to a protractor.
  Supported by corporations who care about education in the construction industry.  
  Mastering FInish Carpentry DVDs