👙 Bra Size Calculator
Measure in inches or centimeters — we'll handle the rest
👯 Your Sister Sizes
How to Measure Yourself
Measure your band (underbust)
Wrap a soft measuring tape snugly around your ribcage directly under your bust. Keep it level and breathe normally. Round to the nearest whole number.
Measure your bust
Wrap the tape around the fullest part of your chest, keeping it parallel to the floor. Don't pull too tight — the tape should just touch your skin.
Enter both measurements above
Our calculator determines your band size, cup size, and equivalent sizes in all international sizing systems.
How is Bra Size Calculated?
Your bra size is made up of two parts: the band size (a number) and the cup size (a letter). The band size is based on your underbust measurement, rounded up to the nearest even number. The cup size is determined by the difference between your bust measurement and your band size.
For example, if your underbust measures 31 inches, your band size is 32. If your bust measures 35 inches, the difference is 3 inches, which corresponds to a C cup. So your size would be 32C.
Sister sizes are bra sizes that have the same cup volume but different band sizes. If your size is 34C, your sister sizes are 32D (smaller band, larger cup) and 36B (larger band, smaller cup). Sister sizes are useful when your exact size isn't available.
Studies suggest that up to 80% of women wear the wrong bra size. Getting properly measured can make a huge difference in comfort and support.