Bra sizes chart: A bra size chart combines band size (measured around the ribcage) and cup size (which reflects the difference between the bust and band measurements) to determine an individuals correct fit. For example, a 34B means a 34-inch band with a B cup size. These charts often display sizes in a matrix or grid format, with international conversionslike UK, EU, US, and Japanese sizingand may include tips for determining a sister size, which helps adjust fit when one measurement changes but the other does not. A well-labeled chart is essential for proper support, comfort, and breast health.