In addition to the foot lengths in the size chart (see pictures), here are the Shoe Undersole Lengths to help you further!
AU 5 BABY - 14.2 cm
AU 6 BABY - 15.3 cm
AU 8 JNR - 16.5 cm
AU 9 JNR - 17.4 cm
AU 10 JNR - 18 cm