A perfect chin, conventionally speaking, extends to just behind a vertical plane dropped from the vermilion border of the lower lip in profile view.
In simpler terms, imagine drawing a straight line down from the edge of your lower lip. The ideal chin should reach just a little bit behind that line. If the chin doesn't reach this point, it's often considered "deficient" and may be a candidate for augmentation. According to the provided reference, this is a common guideline (1-3) for assessing chin projection.
