To get the correct bra size, the first step is to measure before shopping.

What to do…

Step #1: To calculate your band size, snugly wrap a tape measure around your rib cage just beneath your bust, where the bra band would normally rest.* If the number is odd, add five inches to the band size—for example, if you measure 33 inches add five inches, and your band is 38 inches. If the number is even, add four inches—for example, if you measure 32 inches add four inches, and your band size is 36 inches.

Step #2: Then loosely measure your chest at the level of your nipples.

Step #3: To determine your cup size, subtract the band measurement from the bust measurement. For example, if your bust is 38 inches and the band 35, then the difference is 3. Refer to the chart below. That corresponds to a “C” cup size, or a 38C.

Finding Your Cup Size

The difference in inches: 0 1 2 3 4 5 6 7
Your cup size is: AA A B C D DD DDD, F G

Important: Measurements are a good starting point. But bras are as irregular as jeans in sizing, so they should always be tried on. Sometimes a particular style is just not right for you. Also, it’s important to remember that the size you arrive at through measuring may not apply to all bras.

Note: Good-fitting bras can be found in all price points. The longevity of the bra, however, depends on quality and care. To extend the life of a bra, wash it in a lingerie bag with a mild detergent that contains no bleach and hang it to dry. Professional bra fitters typically can be found in lingerie shops or women’s clothing stores.

*For both measurements here, round up to the next whole number in inches.

Source: Elisa Lawson, a certified prosthesis specialist and certified mastectomy fitter (CMF) who operates the Women’s Health Boutique at Mercy Medical Center’s Weinberg Center for Women’s Health & Medicine in Baltimore. Lawson has fit bras for more than 40 years.