1) While wearing a regular bra (no sports or compression bra), measure around your ribcage. That is your band number.

2) Measure across the fullest part of your bust.

3) Subtract the band size from your bust size.

Example: If the band is 34″ and the bust is 38″, the difference is 4″. Each inch represents a cup size, you are a 34D and your size would be 32-36D in Betterly.