We know that sizing can be difficult when manufacturers lump sizes in categories that, when combined, may not fit the unique you. You can use these sizing resources to have a good chance at getting the correct size. Remember that different constructions of undergarments - like sport bras and reduction undergarments - meet different goals and will have a different fit. The most important thing, bar none, is that you look good and feel comfortable. You are you: be you, comfortably.
Just My Size Fitting Video - This video is very helpful in finding the right size for JMS and similar bras.
Bra Sizing Charts - At this link, you'll find charts that can help find the correct size for you for a particular product.
International Bra Sizing Charts - We're in the U.S. and the sizes shown on our site are U.S. / Imperial. These charts can help explain what EU size is at least approximately equivalent.