85pc of women wear bras that are wrong size
Millions of women could be wearing the wrong-sized bra because traditional fitting methods do not work.
A sports scientist has found that the more straightforward "best-fit" approach is better than the old tape measure way of choosing a bra.
The study, published in the journal Ergonomics, found that in three-quarters of cases the tape measure led to the wrong size being chosen contributing to an estimated 85pc of women in the survey wearing the wrong sized bra.
The study measured 45 women using both the traditional method and the best-fit approach, which is based on a set of five criteria which 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 76pc of women and underestimated the cup size in 84pc.
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.
Jenny White of Portsmouth University who carried out the study said: "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 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.
Miss White said: "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."