Let's see... I took a print of a Halo Spartan, printed it on DIN A4 paper (normal size) about 26,7cm tall. My height is about 191cm. I added 4cm for compansation as said in the tut.
so the helmet height is 4,5cm on the pic. So at the end i got a height of 32,85cm.
Thats actualy about it.