United Kingdom Size 30C to US: 30DD

United Kingdom Size 30C: Corresponds to a ribcage band of 76.2 $\text{cm}$ (30 $\text{in}$), bust volume cup size 30C, and recommended sister size 32B.

US: 30DD: Corresponds to a ribcage band of 76.2 $\text{cm}$ (30 $\text{in}$), bust volume cup size 30DD, and recommended sister size 32D.