Gonial angle

The gonial angle is the angle at the corner of the jaw, formed where the vertical branch of the mandible running up toward the ear meets the horizontal branch running forward to the chin. A smaller angle is a sharper, more defined jaw; a larger one is a softer, more open jawline. The adult range runs roughly from 110 to 130 degrees, and around 120 is the usual reference for a jaw that reads as defined. It is properly measured in profile or on a radiograph, so any figure taken from a front-facing photograph is an approximation. The angle is bone, and it does not change in an adult without surgery. What changes is how it reads: fat over the jaw, masseter size, posture and — as with every facial measurement — the height the camera was held at.