Fitting: Size chart is accurate, recommended size chart is comfortable fit for average wide fitting, for great snug fit foot length the same as the full length of the shoes.
Narrow fitting will reconmend to half size down for a better fit, if you prefer room to grow, stay with the size chart, never upper size, it will be too roomy to dance.
If you are adult size narrow fitting ( will not growing ), half size down will recommended, that will be a comfortable great fit.
If you are fast growing and not a narrow fitting ( under size 5 ) upper half size will give 8-10 mm for growing.
Size chart
Pls note, shoes size was lable in US size which is one size bigger than AU size.

Here is a guide for you to determine your size.
Stand up with the heel attach to the wall and measure the distance between the wall and the very last end of the biggest toe, to have you foot length.