Step 1 – The Back or Underband Size

Keep your bra on (unpadded) and measure in inches around your
rib cage directly under your bust and underneath the wire of the bra
When measuring, you should always round down! Your underband
should be snug, e.g. if you achieve 29½ ins then round down to 29 ins.

If it is an even number – add 4 ins
If it is an odd number – add 5 ins
This gives you the underband or back size.

For example: your underband measurement is 29 ins
then add 5 ins – you are a 34.

Step 2 – The Cup Size

Now measure around the fullest part of your bust.
The full bust measurement less underband = cup size
When measuring cup size, you should always round up! The over bust measurement should be generous,
e.g. if you achieve 34½ ins then round up to 35 ins.

34 Back size & 34 Full Bust size = A cup
34 Back size & 35 Full Bust size (+1" difference) = B cup
34 Back size & 36 Full Bust size (+2" difference) = C cup
34 Back size & 37 Full Bust size (+3" difference) = D cup etc...