Measure band size
Using a tape measure, measure your underbust. Make sure the tape is parallel with the ground, and you've exhaled to get the smallest measurement possible.
Measure for cup size
Stand straight, with your arms at your side and measure at the fullest part of your bust (while wearing a non-padded bra). Make sure the measuring tape is parallel with the ground and not binding.
Subtract your band size from your bust measurement and refer to chart. Example: 37 inches (bust) – 34 inches (band) = 3 inches. That’s a 34C.