Place the measuring tape directly under your bust, parallel with the ground. Breathe normally, and measure after you’ve exhaled. Take your band size in inches.
Measure your bust at the fullest part of your bust, wearing an unlined, non-padded bra (not over your clothes!), making sure that the measuring tape is parallel with the ground.
Proper bra measurement is crucial in ensuring that you have the best-fitting undergarments. Too many women spend money on purchasing well-fitting clothes but spend less attention and time on what they wear under them. Bras that are too small can cause back pains and shoulder aches, and bras that are too large will not provide enough support.
Underbust +0: Place the measuring tape directly under your bust, parallel with the ground. Breathe normally, and measure after you’ve exhaled. Take your band size in inches, and round to the nearest even number. It should be as snug as possible but without digging. Use the chart below to find your band size. Remember that inches do not equal size, meaning 34 inches does not equal a size 34 band.
To measure your cup size, measure your bust at the fullest part of your bust, wearing an unlined, non-padded bra (not over your clothes!), making sure that the measuring tape is parallel with the ground. Your cup size is proportional to band size, which means that your cup size is actually the difference (in inches) between your band size and the fullest part of your bust. 1” is an A cup, and each additional inch increases the cup size alphabetically.
The band should be snug, but not too tight. It is the band that mostly supports your breasts, not the straps. You should be able to put no more than 2 fingers under your band. If it’s too tight, go up one band size at a time; if too loose, go down.
It should be lying straight across your back. If the bra is too small, it will squeeze the flesh on your back and front, making unsightly bulges. If your bra rides up, it’s too loose and you should go down a band size; if it cuts into your flesh, it’s too small and you should go up a band size
Your breasts should not bulge outside your cups either in the front or to the side under your armpits. If it is an underwire bra, it is correct if the end is pointing towards the middle of your armpit. If it’s too small, it will dig into your flesh and hurt, and you should size up.
The “gore” — the center of the bra, often where the underwires meet — should touch the sternum. When the gore is at the sternum, it makes for the best fit.
If the bra still doesn’t fill just right, you might try with a Sister Size. To correct for the variance in manufacturers’ sizing, “sister sizing” is a quick way to find a bra with a better fit. Sister sizes are the sizes that surround your current bra size.
To go down a sister size: reduce your band size by 2, but take your cup size up by one (e.g. 36C’s sister size is a 34D)
To go up a sister size: increase your band size by 2, but go down one cup size (e.g. 36C’s sister size is a 38B)