Grams of ground bud. So if you put in 14 grams to make your cannabutter you would have 56 servings at minimum dose. That's the measure I go by. How big a serving requires you put an objective value on a subjective experience, the potency of your weed, and one's tolerance. Commercial stuff is more objective. Almost all dispensary products post thc content on the package. 10 mg thc is more often referred to as a starting dose. So if you have a triple strength Bhang bar (185 mg thc) and it says 4 servings per package that would be 45 mg per serving. 1/4 serving is really a serving. I don't have a big tolerance but I took a 1/2 serving and it was a little creepy for a while. If Maureen Dowd ate a whole bar off the go she must have been pretty fried.
http://www.thestranger.com/seattle/a-beginners-guide-to-ingesting-marijuana/Content?oid=20059080
http://www.thestranger.com/seattle/a-beginners-guide-to-ingesting-marijuana/Content?oid=20059080