Kids’ Shoe Fit Guide. U.S. sizes. Print on 8.5” x 11” paper, at 100% size. Find your child’s size. Somehow or other, convince your child to stand on this paper with his or her heel against the Place Heel Here line. If you can get them to put their weight on the foot and relax their toes, even better. Draw a line to mark the end of the longest toe.