It is important to select the correct size.
Here is a table showing the size range with each length of the shoe given in centimetres and inches. This image is not to scale but just to give you an idea of the length of the shoe. All you need to do is measure your little one's foot from heel to toe and order a size that is at least 1cm larger than the child's foot length.
That extra length is essential to allow their toes to wiggle, muscles to form and their feet to grow.