The tricky thing with menstrual cups is that you have to try them to see how they fit your unique needs. The difference between sizes of menstrual cups is quite minimal (in millimetres!) and it's technically possible for many sizes to fit you. But one size will fit you best, and that size is likely the size that you feel the least inside of you - so the least noticeable. It's also important to note that there is no global standard for menstrual cup sizing quite yet; some brands label their cups as size A, B, C, some 1, 2, 3 and others, like ours, as "Small," "Medium" and "Large." Contact our support staff if you ever want to chat it through! We have access to advice from our gynecologist on Board, Dr. Ardelle Piper to help us all make the best decision for you.