I tried a similar pair of Kamik boots on my toddler at a local store in the same size (I think they were the Waterbug variety) and then ordered these assuming they would fit him.  WRONG!  I literally couldn't even get his foot into these.  I pulled out the inner liner to see exactly how they weren't fitting, and they were extremely narrow.  I was really disappointed because they are obviously well-made and super-warm boots.  For reference, he wears about a 7 or 7.5 in most shoes, and I ordered these in an 8.