People come in all sizes and shapes, but there are a few underlying rules which are invaluable for getting proportions accurate in figure painting. Once you're familiar with these, it's also easier to observe the natural variations that occur in people.
Height: If the head (from the end of the chin to the crown) is taken as a unit of measurement, the body is about seven-and-a-half heads tall. There are three head lengths from the end of the spine to the base of the skull. Midpoint is at the genitals.
Feet and Hands: Feet and hands are surprisingly big. Feet are about a head long and hands are easily the same length as from the chin to the forehead.
Arms and Legs: If the arms are hanging freely, the wrists are around mid-point and the fingertips mid-thigh. In women, the elbows are slightly above the waist.
Shoulders: In a man, the shoulders are about two heads wide.
Buttocks are about a head tall.
