If selling to a general audience, there is no tool or a rule that can help you decide the size to order. However, you can assume that the majority of consumers fall somewhere in the middle sizes. Based on our past experience, we recommend ordering shirts in the following ratio:
S : M : L : XL : 2XL ---- 1 : 1 : 2 : 2 : 1.
Once you are able to sell the initial batch, you would have a better idea of your customer base for future reprints.