We needed to get our one year old snow boots and had a really hard time finding any in his size locally.  I was nervous about purchasing online as I would have preferred to have tried them on him.  At the time of ordering, he was a size 4 but they were getting tight so we purchased a size 5 in the boots.  They are a little bit larger than I expected but we just put on thick socks with them and they fit well.  My only complaint is that they come off very easily - he regularly loses them when running in deep snow.  This could be because they are slightly big so I will update if that changes as he grows over the winter.  The price is steep for a boot that will only be worn for one season but they are so warm and well made that I know they will last for a number of little ones.  Temperatures have been in the low 20's as a high here the last week and when we take these off him his feet are super warm.  Well worth the price.