Bra Sizing How To Guide

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Jill Daniels, Freelance Medical Writer

Jill Daniels is a freelance health writer based in New York City. She spent several years writing for WebMD, including their Weight Loss Clinic and Fertility Center programs. Jill has also written/reported for publications including InStyle, People and Women's Own. She received a degree in journalism for Northwestern University's Medill School of Journalism.


November 15 2007

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Are You Wearing the Right Size Bra?
It's pretty obvious when shoes or pants don't fit quite right. Unfortunately the same doesn't hold true for bras. Statistics show that as many as 85% of women are wearing the wrong bra size. It's time to give your bust the support and shape it deserves.

Bra sizing is not an exact science and there's no bra size calculator that's absolutely accurate. Rather, differences in breast spacing and shape can affect how a bra will fit. It's important to note that there can also be differences in the same bra sizes of different models offered by different bra manufacturers.

Below are some tips for how to measure your bra size (whether you have had breast enhancement or not). These methods generally work for most, but not all, body types. Use what you calculate as a starting point to find the bra size that works best for your body.

Do-it-Yourself Bra Sizing
To find out what bra size you should be wearing, start with the band size. Use a soft tape measure to measure around your rib cage, right underneath the bust. Be sure the tape measure is low and snug on the back – and that it is even around the front. Add 4 if the number is even and 5 if the number is odd to arrive at your band size. For example, if your rib cage measurement is 30 inches, plus 4 inches equal a 34-inch band size. If your rib cage measurement is 27 inches, plus 5 equals a 32-inch band size.

There are a couple different ways to find your cup size. You may want to try both.

Method 1: Use a tape measure to measure completely around the fullest part of your bust and around your back. Make sure to hold the tape measure straight, but not tight. The difference between your band measurement (see above) and your bust measurement equals the size of your cup. Each inch of difference is equal to one cup size. For instance if your band size is 34" and your bust size is 36" you wear a B cup.

If the difference between the two measurements is:

Less than 1"

AA cup

1"

A cup

2"

B cup

3"

C cup

4"

D cup

5"

DD cup
6" E cup (also DDD)


Method 2: Use a tape measure to measure across the fullest part of the breast (across the nipple) from the inside of the breast at your breastbone, where the cleavage is, to the outside of the breast, near the underarm. Find the measurement number on the chart below to learn your cup size. This method can be especially helpful for women with very large or very small frames, unusual breast shapes, and women who have large implants on small frames.

Identify your cup size by finding your breast measurement on the chart below:

7"

A cup

8"

B cup

9"

C cup

10"

D cup

11"

DD cup
12" E cup (also DDD)


While these bra sizing methods are generally reliable, every woman's shape is different – and it can be very difficult to measure yourself properly. If you think you are not getting the correct bra size, you may want to consider going to a specialty bra store and having a professional bra fitting. Many boutiques or department stores have trained staff on hand to help with proper bra sizing.

How Your Bra Should – and Should NOT – Fit

  • Your new bra should fit snugly on the last setting, the loosest hook. That way when the bra stretches with wear, which it inevitably will, you can adjust it by fastening it on the tighter settings.
  • The band should fit across your back below your shoulder blades. Many women secure their bra band too high on their back, forcing the band to ride up and the cup to drop forward.
  • Bra straps should not dig into your shoulders or leave red marks. The band of your bra should be snug enough to provide most of the support you need, and your bra straps should be comfortable.
  • A common mistake many women make is choosing a bra with cups that are too small and a band that is too big. Your bra should never "cut your breasts in half." If this happens, the cup you're wearing is too small. Similarly, if your breasts are spilling out the sides or bottom of your bra, you need to get a bigger cup.
  • You shouldn't feel pressure from the under wire of your bra, and the center of your bra should touch your breastbone.

Bra Sizing with Breast Implants
If you have implants, you should measure your band size exactly the same as if you didn't have implants. The band size depends on your ribcage size, and that doesn't change with breast augmentation surgery.

As for measuring cup size, you can try both bra sizing methods described above. Some women with breast implants find that method 2 works better because it takes into account the fullness of the implant. Breast implants tend to be wider than natural breasts and often they are more ample. Therefore, even if you think you should be a C cup, you might want to try a D cup to get the right size. And if you are considered a "full cup," that typically equates to a half a cup size larger.

Also, women who have had breast augmentation  may find that "natural form" bras don't fit very well because they bag in the nipple area, particularly if there was little natural breast tissue preoperatively. Bras with Lycra may be helpful in this case, because they conform better to the breast shape created with implants.

Why and When Your Bra Size May Change
There are a variety of factors that can affect a woman's bra size, such as weight fluctuations, pregnancy, age, exercise, and birth control pills. In fact, it's common for a woman to wear many different bra sizes throughout her life. It's a good rule of thumb to check your bra size every 6 months or year, or when you know your body has changed. Remember, a good bra can make a world of difference for your figure – and your comfort.