Poly's are calculated out of triangles. Triangles are calculated out of faces, a face do not necessarily need to be quads (it can be higher, but no less than a triangle). A basic cube would be made up from 6 faces, but because the faces are quads, they need to be split into triangles to be shown in openGL, openGL would handle this job automatic. Anyway, the cube wil then be made up off 12 polys.
So if you have a head totaly made up from quads as faces the poly count wil be equal to the face count times two.
But its seldom that a head is made up from just quads, usualy most quads, some triangles and some pentagons here and there. It's just a mather of how you model.
I strongly recomend you should take a look at some poly modeling tutorials (3dcafe.com, highend3d.com etc..)
- Kjetil