Here is the official Posh Panda Size chart
The best way to determine which size you will need is by measuring in inches your child's foot on a hard flat surface while standing and add half inch for growing room. As every child's foot is different I only have the age guide more for a gift reference. Please make sure to double check your measurements as I cannot do size exchanges for ordering the wrong size.
New Toddler/Youth Rubber Sole Sizing is as follows:
Womens sizing is as follows: