1. Place the measuring tape flat against your skin – directly under your breasts. · 2. Tighten the measuring tape a little and round the measurement up or down to. The measuring tape should be somewhat loose and measured at the fullest part of your chest. BRA SIZE CONVERSION CHART. TH, 32C, 32D, 34B, 34C, 34D. Follow these bra fit steps · Measure your band. Wear a lightly lined (non-push-up) bra so your breasts are as close to natural as possible. · Now measure your bust. The bust size is the loose circumference measured around the chest over the fullest part of the breasts, while standing straight with arms to the side, and wearing a.