You can use a Catra laser protractor to measure the edge angle precisely. Otherwise, you can use a sharpening system with set angles, such as the Sharpmaker, EdgePro or Wicked Edge in a trial and error to find the angle at which the stone is parallel to the edge, usually with the help of a Sharpie and/or Loupe.
I reprofile all my edges to 30 degrees inclusive -- 15 degrees per side. It's a good angle for good steels, and it matches the Sharpmaker's pre-set angle, which I use for quick touch-ups.
Benchmade, as Noctis says, usually has less acute angles.
Factory knives are often uneven, with the grind on one side being steeper than the grind on the other side. Reprofiling cleans that up. I use the Wicked Edge for reprofiling and major sharpenings.