In our experience it's best to order the size up. So, if you're in between a medium and a large, order the large. If your not happy with the size, we'll happily send you a replacement at our cost.
You can also see the Size Guide for all products here:
United States Sizes: https://zaggora.com/pages/size-chart
UK, Europe Sizes: https://uk.zaggora.com/pages/size-chart