I am a true womens size 6 and the J4 (junior) fits perfect.  It fits exactly as if it were a womens 6.  No difference.  I wish Crocs would make these in the ballet closed toe flat.  Im not a fan of the other ballet flats they have for women.  Boring and just thick and rubbery.  I don't think people realize that women also like a bit of glitter as well as children so to make these closed toe, it would be super!  It would also help some people who complain about the peep toe opening rubbing.  Please make more colors and make a closed toe version!!