Sizing can vary between brands and designers. Sometimes, the size chart for an item will be based on the US size chart of S, M, L, XL etc. Other times, the size chart will be based on the item as it lies flat. In this case, to help you determine what size you would be for that item, I recommending picking something that you already own, lying it flat, and measuring as shown in the image below. Then, compare your findings with the item you're looking at. When in doubt, my recommendation is to always size up! And please, keep in mind that if it doesn't fit, I'm happy to swap it out for you at no extra cost. You will only be responsible for return shipping.
To keep your new clothing in the best possible condition, we recommend cold water washing with like items, or in it's own mesh laundry bag. We don't recommend putting your clothes in the dryer.