Bra Size Calculator

Bra sizing starts from two measurements: the snug underbust and the bust at its fullest point. This rounds the underbust to the nearest even inch for the band, then reads one cup letter for each inch between bust and band, which is the convention set out in the r/ABraThatFits sizing guide rather than the older method that adds four inches. Inches or centimetres go in, and US, UK and European labels come out, along with the sister sizes that carry the same cup volume on a different band. Cup lettering above D runs differently between countries and between brands, so the same measurements can carry different labels on two racks.