Step 1: Find your band size

While wearing your best-fitting unpadded bra, wrap a measuring tape around your ribcage. It should be snug, but not too tight. This measurement is your under bust.

Use your under bust measurement and the chart below to determine your band size.  

Step 2: Find your bust size  

Next, wrap the measuring tape around the fullest part of your breasts. Again, it should be snug, but not too tight. This measurement is your bust.

Step 3: Find your cup size

Subtract your band size from your bust size. Use the difference and the chart below to determine your cup size.

For example: Band = 36. Bust = 39. Cup Size = C (39 - 36 = 3 difference). This would be a 36C bra size.