Bra sizing normally combines a band number with a cup letter. This page asks for two measurements—underbust and bust—and returns a page-specific starting band, cup, bust difference, and three nearby sister sizes. That makes it useful for narrowing an online-shopping or in-store try-on range.
It is not a brand-size converter and does not model cup depth, style, fabric stretch, or individual breast shape. Its job is to give you a reproducible starting point, not to declare a guaranteed perfect fit.
Wrap the tape around the torso directly below the bust. Keep it level and snug without digging in. The current input range is 60–120 cm. It determines the page band reference and contributes to the bust difference.
Wrap the tape around the fullest point of the bust. Keep it level and avoid compressing the tissue. The current input range is 70–130 cm. Together with underbust, it determines the page cup index.
It rounds the underbust to the nearest 5 cm band reference, then maps the bust-minus-underbust difference to the page cup index in 2.5 cm steps. It is a starting size, not a universal international conversion.
Keep the underbust tape level directly below the bust and snug without digging in. Measure the bust at the fullest point without compressing tissue, keep the tape level, use the same unit, and repeat the same landmarks.
They are nearby band-and-cup combinations that narrow the try-on range; they do not guarantee identical volume or comfort across brands.
Country systems, brand patterns, fabric stretch, cup depth, style, and individual breast shape all affect real fit. Treat the result as a starting point and confirm on the body.
Estimate a starting bra size and sister sizes from underbust and bust measurements; check the measuring method and brand chart before trying it on