I'm usually a S/M depending on the type of clothing I'm buying because I have wide hips with a thin upper-body. I ordered a small, intending on wearing them high-waisted and it fits perfect! I love how you're able to tie the top of the romper in SO many different ways and the fabric is soft af (feels like pajamas). I wear pasties with this type of romper since it's completely backless and it works dressed up or down!