Bra Size Calculator  You'll need a tape measure and a mirror.
Make sure you're wearing an unpadded bra. If you're wearing a
thin top, you can leave it on, but any thick layers (sweater,
hoodie) will have to go.  Find your bra size 1. Measure your
chest  Stand straight and relaxed in front of a mirror with your
arms down, breathing normally. Now you're ready to measure your
chest. To get the most accurate measurements, it's a good idea
to have someone help you.  Wrap the measuring tape snugly around
your chest, right under your arms. Make sure the tape is not
twisted and that it's parallel to the floor all the way around.
2. Measure your rib cage  Now it's time to take your rib cage
measurement. Wrap the tape measure snugly around your body just
below your breasts.  If someone is helping you get your
measurements and you're wearing a bra in which your breasts are
sagging (even a little bit), pull up on your straps to lift your
breasts to the place you'd like them to be, then have your
friend measure your rib