Bra Size Charts
Different countries and brands use different size systems. A 36G in a US sized bra is the same size as a 36F in a UK sized bra. Both size systems express the the same cup volume and band size same, they just do so in a different "bra language".
We tend to use UK sizing as a default at Broad since most of the brands we carry use this size system, but we do carry brands that use other size systems.