Australian sizing is not recognised as a standard size by Saucony.
Saucony is an American brand and all sizes on our website are based on US sizes. We recommend checking any shoes that you currently own for a US/UK/EU size.
Sizing does vary between brands and even different styles in the same brand. The size guide is a recommendation to assist in choosing the best size for you but as every foot is different you may not know for sure until you try a size on.