Bra Size Calculator – US, UK & EU Sizes

How to Find Your Correct Bra Size

Finding your correct bra size starts with two measurements: underbust and bust. The underbust measurement is taken snugly around your ribcage, directly under your breasts. The bust measurement is taken at the fullest point of your bust, usually across the nipples, while wearing a non-padded bra or no bra. Stand straight with arms at your sides for the most accurate measurement.

Your band size is determined by the underbust measurement, typically rounded to the nearest even number in US/UK sizing. The cup size is calculated from the difference between bust and band measurements — each inch of difference corresponds to one cup size. For example, a 1-inch difference is an A cup, 2 inches is a B cup, 3 inches is a C cup, and so on. EU sizing uses centimeter-based band sizes rounded to the nearest 5 cm.

Sister sizes are sizes with the same cup volume but different band sizes. For example, 34C, 32D, and 36B all have the same cup volume. If your band feels too tight, try going up one band size and down one cup size. Bra fit varies significantly between brands and styles, so these calculator results are a starting point. A well-fitting bra should have a snug band (you can fit two fingers underneath), cups that lie flat without spillover or gapping, and straps that stay in place without digging in.