Step 1 - Determine your band size

Take a snug measurement around your rib cage directly under your bust.
Match this measurement with the corresponding band size in the chart below

Step 2 - Determine your cup size

Take a loose measurement around the fullest part of your bust, making sure the tape measure does not indent the breast tissue.

Subtract the band size determined in step one from the bust measurement. The difference between the bust measurement and the determined band size indicates your cup size: