Shoes run true to size. Please use your normal size. Nina is wearing the size 9 just as she typically does from other brands. The size measurement is for the length of the actual shoe. You can measure your child's foot by tracing it and adding 1/4" to 1/2" for a size as well. Sizes 3-5 will have anti slip soft soles and 6 and up with have hard soles. Soft soles are better for the development of new walkers.