Band and Cup Check
Start from a size you already wear and a problem such as a riding band or a gaping cup. It suggests the next size to try. A fit check only — not medical advice, and not a promise the next size will fit.
Frequently asked questions
Is this medical advice?
No. It is a starting suggestion from common sister-size and cup-change rules. Not a fitting room, not medical advice, and brand charts still vary.
Is gaping a sister size?
No. Gaping usually means one cup down on the same band. Sister sizes change the band and the cup together.
Is my data sent to a server?
No. This calculator runs entirely in your browser. Nothing you type is uploaded or stored by Qivtools.