Some experts estimate that up to 85 percent of women are wearing the wrong bra size. A properly fitting bra can improve the way you look in clothing and provide comfortable support that does not pinch or cause tell-tale red marks on your shoulders. Calculating your correct bra size is as easy as A,B,C...D.
Put on a non-padded bra or go braless. Using a cloth or flexible measuring tape, measure around your chest directly under your breasts, making sure to keep the measuring tape level. Your measuring tape should be snug, but not uncomfortably restrictive.
Round the measurement you got in Step 1 to the nearest whole number. If you get an even number, add four inches to it. If you get an odd number, add five inches to it. Write down this measurement. This measurement represents your bra's band size.
Use your cloth or flexible measuring tape to measure around the fullest part of your bust while keeping the measuring tape level and slightly loose. Keep your arms down while taking this measurement. Round this measurement to the nearest whole number and then write down this measurement. This measurement represents your bust measurement.
Subtract your band size (the measurement you obtained in Step 1) from your bust measurement (the measurement you obtained in Step 3). If the difference in inches is 0, your bra's cup size is a AA. If your measurement is a 1-inch difference, then your cup size is an A cup; if your measurement is a 2-inch difference, then your cup size is a B cup; if your measurement is a 3-inch difference, then your cup size is a C cup; if your measurement is a 4-inch difference, then your cup size is a D cup; if your measurement is a 5-inch difference, then your cup size is a DD cup; if your measurement is a 6-inch difference, then your cup size is a DDD or F; if your measurement is a 7-inch difference, then your cup size is a G cup.