I bought a S and a M as I wasn’t sure which bodysuit would fit best. I’m usually a standard Australian size 8 or S. The small fit well but the medium was way too big, there was a massive difference between the two sizes. The medium also had a lot of spare/ baggy material at your lower back, so definitely size down if you have a small waist. I have a longer torso and this design was perfect for making sure my boobs were covered. Gets the job done if you’re using this as part of a Halloween costume, the quality is as expected for a one time wear outfit.