We get asked this a lot – which is unfortunate because there's no real answer. Label size and shape depends on the type of product you're packaging, what regulations need to be taken into account, how much information you wish to include, what images you want to display on the product label, and so on. Products on the supermarket shelf using the exact same containers often have very different label sizes, so it's important to understand that there's no such thing as a "standard size".
Arriving at the correct size and shape is a critical part of the product label design process, and that's not something Wizard Labels gets involved in. Our contribution is to print high-quality custom product labels from customer-supplied artwork. The optimal size and shape of your custom product label is impossible for us to predict – although we do like to give general tips and design insights through our blog.