Are 8 Out of 10 Women Really Wearing the Wrong Bra Size?

But Dr. Pechter didn�t reach his estimate through surveying a large and diverse sample. Instead he used anecdotal evidence from publications like Good Housekeeping, Ladies� Home Journal and the Playtex Fit Guide. (He also studied only women who reported wearing cup sizes AA through DDD. Today you can find bras in sizes up to an O cup.)

Jenny Burbage, a sports biomechanist at the University of Portsmouth in Hampshire, England, has made studying breasts (and how to support them) her life�s work. In one of her studies, �Evaluation of professional bra fitting criteria for bra selection and fitting in the UK,� Ms. Burbage noted that �it has been suggested that 70 to 100 percent of women are wearing the wrong size bra,� citing Dr. Pechter�s work along with few other small studies to reach that range.

�There aren�t many scientific papers available which have effectively looked at issues of bra fit and the number of women who may be wearing the wrong size bra,� Ms. Burbage said in an interview. Anecdotally, she sees �hundreds and hundreds and hundreds of women� who come through her lab struggling with fit issues.

Like Ms. Gergely, Dr. Burbage said the issue was not that people were simply wearing an incorrect size but that they often didn�t know how to check for the best fit. �Women are going to be different sizes in different bras,� she said. �I might have three or four different bra sizes based on what bra I�m wearing and what manufacturer that comes from.�

The lack of standardization can be frustrating, but it also gives women more opportunity to find styles and shapes that work for them.

The �Right� Size

If fit is relative, why are retailers still fixating on the idea that the right size exists?

It�s a new approach for the lingerie industry, with gender and size inclusivity outpacing hypersexualized marketing. But, like Victoria�s Secret, they insinuate the same thing: that you�re wearing the wrong size and that they can help you find the right one.

�We�ve always focused on this idea, �Are you wearing the right size?�� said Heidi Zak, the ThirdLove co-founder and chief executive. According to Ms. Zak, the company has consistently used the concept that people are wearing the wrong size in its marketing. She considers the statistic an invitation for shoppers to find bras that work, not an admonition.

�I think that we�re actually trained as women to be like, �If you don�t wear a cookie-cutter size, then there�s nothing for you,�� she said. To combat that sentiment, ThirdLove sells bras in cup sizes AA to I, including some half-cup options.

Cora Harrington, the author of �In Intimate Detail: How to Choose, Wear, and Love Lingerie� and editor of the Lingerie Addict blog, eschews the oft-repeated 80-percent-plus number in her book. She couldn�t verify it, and she is not interested in repeating a figure that makes people feel as if they�ve failed before they even start shopping.

�I�ve heard that stat for at least as long as I�ve been writing about lingerie,� Ms. Harrington said. Phrasing bra fitting as a chore, she said, or as something women are doing wrong, or that they don�t really know their bodies very well, doesn�t �invite people to come in and learn more about bras.�

Think Beyond the Size on the Label

Ms. Harrington recognizes that shopping for a bra can be difficult but said there has never been a better time to do so. Online shopping means that people aren�t limited to the options in their neighborhood, and lingerie brands are now introducing lines in a greater range of sizes beyond D cups. (Rihanna�s Savage x Fenty line is doing it.)

Ms. Harrington recommends reading reviews on blogs or forums, trying on as many bras as possible and going to specialized shops where expert fitters can provide feedback and new options. She said that once you find a style you like, you can look for discounted colorways from previous seasons, but she also encourages people to support boutiques when they can.

Finding a bra that fits well is tricky not only because sizing varies by brand, but also because of how sizes are related to one another.

LaJean Lawson, a scientist and consultant for the Champion sportswear brand, explained that the cup size is usually based on the difference between the band and bust measurements (below the rib cage and over the fullest part of the breast). The cup is measured by volume, and, confusingly, that volume can stay the same as you move down a band size and up a cup size, or up a band size and down a cup size.

This is called sister sizing, and it means that, theoretically, a 34C could have a similar volume to a 32D or 36B. But bras may fit differently based on the shape of the bra and the band measurements, how your breast volume is distributed on your body and, again, by brand.

Because there are so many variations in bra styles and sizes, finding a comfortable and supportive fit involves trial and error. (Wirecutter, the review site owned by The New York Times, has recommendations for how to shop for bras and check for fit.)

But it may also mean accepting that as your body changes during menstruation, pregnancy or regular weight fluctuations, your bra size may change. Experts like Linda Becker, the fitter at Linda�s bra salon in Manhattan, recommend rechecking your bra fit every six months to a year.