Excerpt
We often think of height as something that is relative. In other words, a character only looks tall or short when standing alongside an object whose size the reader is already familiar with.
But this isn't the way it really works. Characters look tall, medium, or short in stature based on their own proportions, regardless of whether there is anything else to compare them to. Artists create this effect by using the character's own head as the unit of measurement to determine overall height. Generally, a cute character is 4 to 6 "heads" tall. An average character is 6 to 7 heads tall. A tall character can be 8 to 9 heads tall. And superstylish characters such as bishounen and bishoujo, as well as gothic characters, can be even taller. On the other end of the spectrum, supercute chibis can be as few as three or even two heads tall!