Face proportions

The proportion of the human face is about 3/5 (either male or female), an approximation of the so-called "golden section".  A 2/3 or 5/8 proportion is just as good.

As you can see the eyes are situated approximately at 1/2 of the height of a human face. We often make this mistake and it is due to deformation by the perspective, ie the angle under which we look at a face.
The common mistake is having a too short forehead (and therefore the eyes too high). This comes from the time when we were children and looked at adult faces from the lower perspective of the child we were. Since most have stopped drawing then, people tend to keep this "perspective" which is not the one as adult!
Hence this common mistake...

"Donna con cappello verde“, Woman with Green Hat By Pablo Picasso, 1939

Based on my experience as portrait painter:

1. the human head is facing us vertically to the ground (proportions change when the subject is looking upwards or downwards) *
2. the head is inscribed within a rectangle with approximate proportions of 2/3 or 3/5 (roughly those of a letterhead). I found these proportions after using many photographs of people with short hairs (or bald) to better locate the actual limit of their skull (haircuts are misleading)
   Note: when drawing a baby’s face this proportion is closer to a square’s: (roughly) 4/5.
3. the ears are OUTSIDE of the rectangle (since they are floppy and their size/shape vary)
4. the eyes are located at (roughly) 1/2  of the rectangle height (i.e. when faces are vertical to the ground)
5. the length of the nose is (roughly) the same as the distance between the center to the eye  corner : they can therefore be inscribed within a circle whose center is situated between the eyes
6. when still the mouth position can be found by drawing a circle inside the rectangle (diameter is equal to basis of the rectangle) – of course any expression (grin, sorrow etc)  will affect the size and position of the mouth…

* this explains why children (or adults who have kept this habit) tend to draw faces whose eyes are situated too high (therefore with a too short forehead):their point of view is as seen from underneath!

Based on these tips, my daughter did the following portraits of herself and her grandparents when she was 14: