Ballet shoes (and even different brands) all have their own strange system of sizing - the sizes do not compare to normal street shoe sizing.  According to the Capezio manufacturer, their toddler/little kid ballet shoes are to be ordered one full size up from their current street shoe size.  Bloch brand kids ballet shoes are to be sized up 1/2 size.  (If you order adult shoes, they're often sized down 2 or 3 sizes...) Any dancewear store will have this information, but unfortunately Amazon doesn't provide this tidbit, so it can be quite confusing as to what size to order.  I hope this helps any future purchasers!