Using a tape measure, I measured the heads and waists of myself and 4 siblings in both inches and centimeters. I saw that by the time a child is about three, their heads slow down their growth significantly. A newborn's head on average is usually about 13.7" or 35 cm. Zoey is three and her head is eighteen inches in circumference, while mine, at thirteen, is twenty-one, Julia and Olivia have the same size heads at about twenty inches at five and eight. Levi's head is about 20 1/2" and He is ten. Zoey's head and waist are almost exactly the same size. Julia's head and waist are the same size as well. It seems that everyone but me has their head circumference the same as their waist circumference!

this is the directions on how to make a graph in google docs. It's how I got this graph:
http://support.google.com/docs/bin/answer.py?hl=en&answer=63728