All measurements stated in inches. BUST: Measure under your arms around the fullest part of your chest. HIP: Measure around the fullest part of your body at the top of your leg. WAIST: Measure around your natural waistline at belly button. If you are between sizes in Onzie bottoms, Onzie suggests trying the smaller size as the fabric is quite stretchy and will form to fit your body as you move and sweat in them.