Wear a non padded bra. Wrap the measuring tape around your back, at band level, under each arm and around to the front. Measure just above your bust, about where the straps meet the top of cup. This measurement is your band size. If it is an odd number, round down to the nearest even number. Or check the chart below to find your band size.
Wrap the measuring tape around your back (at band level), under your arms and around the fullest part of your bust. Make sure the tape is comfortably snug but not too tight. Take a deep breath, hold it, then take note of the number. Find this number in the chart below to determine your cup size.