Traditional bra-fitting doesn't give the best fit, study reveals

March 7, 2012

Women shopping for new bras should throw away the tape-measure and focus on how the garment fits, according to new research.

The work is the first scientific study in the UK to compare the traditional method of bra-fitting, using a tape-measure, with a more straight-forward ‘best fit’ approach based on a set of specific criteria.  It found that in more than three-quarters of cases the tape measure got it wrong.  The researchers believe that this may contribute to the estimated 85 per cent of in the UK wearing the wrong sized bra. 

Sports scientists at the University of Portsmouth measured 45 women using both the traditional method and the best fit approach, which is based on a set of five criteria that considers the under-band, the cup, the underwire, the straps and the front-band.  Compared with the best fit approach, the traditional method overestimated the band size in 76 per cent of women and underestimated the cup size in 84 per cent.  On average the traditional bra fitting method gave a result that was one cup size smaller and one band size larger than the best fit method.

The study outlining the findings is published today in the journal, Ergonomics

Lead scientist, Jenny White from the Department of Sport and Exercise Science, said that the traditional approach could leave many wearing the wrong size bra.  She highlights that the traditional alphabet sizing, developed in the 1930s, reached only up to a D cup and with half the women in the UK being a larger size, the accuracy of the traditional method is questionable.  She suggested that women should subjectively assess their size using the best fit criteria. 

“We measured the same women using the two approaches and found that the traditional method resulted in the underband being too loose and the cup too small.  Using the best fit criteria our fitters achieved a supportive comfortable fit which our participants were happy with. “

“Wearing a well-fitting bra is crucial to achieving good support and helping women look and feel their best.  And it can help prevent back and neck pain and reduce irreversible breast sag.” 

The traditional fitting method using a tape measure is still used today by many well-known retailers.  But since its introduction the size and shape of womens’ bodies has changed significantly and there has been a substantial increase in the average breast size. 

The new study also found that the larger the woman’s breast size the greater the discrepancy between size determined by the traditional method and the best fit method. 

“Using the traditional method we found that the larger the underband size the more erroneous the overall sizing became with some women seeing a difference of more than three sizes.   This has implications for larger breasted women in particular who should be wary of using the traditional method of bra fitting due to the greater sizing inaccuracies.” 

“Larger-breasted women especially may feel self conscious about being measured and be more inclined to fit their own bras but there is a general lack of awareness about the way a bra should fit.” 

“Bra-size is difficult to measure with accuracy which can be affected by breathing, posture and physical characteristics.  The most common mistake is to wear the underband too loose and the cup size too small.  For example, a woman believing her average bra size to be a 34 D may find she is better supported in a size 32 DD.” 

“But finding the right sized bra depends on a number of factors including the woman’s body shape, the shape of her breasts, the type of bra and its manufacturer. “

“It’s important that women realise there are discrepancies between manufacturers’ sizes and they may be a different size in different shops, just as they would be with clothes and shoes.  Finding the right fit can be trial and error but using the set of basic criteria should help.”

The research highlights the need for better education for consumers and retailers in bra fitting which concentrates less on a number and more on good overall fit and comfort. 

Malcolm Ball, Chairman of the Association of Suppliers to the British Clothing Industry, said: "This research adds facts and weight to the increasing body of evidence showing that fit is dependent on personal morphology and comfort.  Formulaic sizing and shaping need to be totally reviewed and new sizing methods explored if the problems of customer dissatisfaction and discomfort are to be addressed."

“The study is of great interest and importance to the future design, marketing and selling of intimate wear as it highlights the difficulties and shortcomings of traditional sizing and labelling with regard to garment choice and fit.”

Miss White said that using a tape measure can sometimes be a good place to start but that women should not become fixated on a number, especially when women’s breast size and shape changes during the month and can alter considerably with age. 

“Women should frequently evaluate their bra size and be prepared to buy a range of different sizes.” 

“There is little overall difference in breast size between a 38 C, a 36 D and a 40 B, the important factors being comfort and support.” 

The best fit method, referred to in the study as the professional fitting criteria, consists of five criteria as follows:


Too tight: flesh bulging over top of band; subjective discomfort “feels too tight”

Too loose: band lifts when arms are moved above head, posterior band not level with inframammary fold


Too big: wrinkles in cup fabric

Too small: breast tissue bulging above, below or at the sides


Incorrect shape: underwire sitting on breast tissue laterally (under armpit) or anterior midline; subjective complaint of discomfort


Too tight: digging in; subjective complaint of discomfort; carrying too much of the weight of the breasts

Too loose: sliding down off shoulder with no ability to adjust the length

Front band

Not all in contact with the sternum

Rating of bra fit

Pass: no errors or if hooks or straps can be adjusted to allow correct fit

Fail: any other ticks

Explore further: Scientists help develop new sports bra fitting service

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