Where Does the 80% of Women Wear the Wrong Bra Size Statistic Actually Come From?

The claim that 80% of women wear the wrong bra size traces back to a mix of a small academic study, a UK retailer's internal fitting data, and decades of repetition without citation. The number itself is probably in the right neighborhood, but the commonly repeated version overstates what any single study actually showed. Here's where it really comes from, and why the underlying problem is real even if the exact percentage isn't as solid as the marketing copy suggests.

Where the Number Actually Comes From

Two main sources get cited, usually without a link back to either one:

1. A small academic study out of Melbourne

A peer-reviewed study, Breast size, bra fit and thoracic pain in young women: a correlational study, conducted at Victoria University in Melbourne, is the study most frequently traced as the origin of the 80% figure. Its actual findings: 80% of the women in the sample wore an incorrectly sized bra, broken down as 70% wearing a bra too small and 10% wearing one too large.

What often gets left out when the number is repeated: the sample was 30 women, all in a narrow 18-26 age range, and all had self-reported thoracic (upper back) pain — the study was investigating a possible link between bra fit, breast size, and pain, not measuring bra-fit accuracy across the general population. A group specifically recruited because of pain complaints is not a representative cross-section of all bra wearers, and 30 people is a small sample to project onto women as a category.

2. Marks & Spencer's internal fitting data

The other commonly cited origin is a study or fitting-data analysis conducted by Marks & Spencer, the UK retailer well known for in-store bra fittings. M&S fitters use a technical fit philosophy that fits the band snugly, and when they measured customers against that standard, a large majority weren't wearing the size the fitters considered correct. That's a real, large dataset — but it's internal retailer data built around one company's specific fitting philosophy, not an independently published, peer-reviewed study with public methodology.

What This Doesn't Mean

Critics who've dug into the citation trail — including detailed write-ups from independent lingerie writers — land on a consistent conclusion: the 80% figure is probably not fabricated out of thin air, but it's also not the airtight, universally-representative statistic it's usually presented as. It's a number that keeps getting repeated because it's memorable and plausible, not because it's been re-verified.

What's Actually Well-Supported

Separate from the specific 80% figure, a few related things are well documented and don't depend on that one number:

• Multiple independent surveys and studies, across different populations and different decades, consistently find that a majority of women report bra-related discomfort, band-riding, strap-digging, or uncertainty about their own size — the exact percentage varies by study, but the direction is consistent.
• A 2006 Harris Interactive study conducted for Maidenform and the North American Spine Society found that 59% of women reported their bra caused back, shoulder, or neck pain — a different, independently sourced figure pointing at the same underlying problem.
• Patent literature on bra-sizing methodology, going back to the late 1990s, independently describes a 70% or more figure as commonly reported in the field at the time — suggesting the general order of magnitude isn't new or invented for marketing purposes, even if the specific 80% figure traces to a small study.

Why the Underlying Problem Is Real Regardless of the Exact Percentage

Whether the true figure is 60%, 70%, or 80%, the mechanism behind it is well understood and doesn't depend on any single disputed statistic: most mainstream sizing methodologies either measure the band at the wrong point on the body, or add inches to the measurement that don't correspond to anything on the actual person. Our full breakdown of exactly how and why that happens is in Bra Measuring Methodologies Explained.

A band that's sized based on an added or relocated measurement, rather than the body's actual rib cage, produces a predictable set of problems: a loose band that rides up, straps that take on weight they weren't designed to carry, and a cup capacity that no longer matches the person wearing it. Those are the same complaints that show up across every study referenced above, independent of which exact percentage is attached to the headline.

How BRABAR Uses This Statistic

We reference the 8 out of 10 figure in our own materials because it's a widely recognized shorthand for a real, well-documented problem — not because we're claiming it as an internally-verified, peer-reviewed number specific to our own customer base. The honest version of the claim is: multiple independent studies, using different methodologies and different populations, consistently find that a majority of women are not wearing an accurately sized bra, most often because the band was measured at the wrong point on the body or padded with extra inches that don't reflect their actual proportions.

Frequently Asked Questions

Is it true that 80% of women wear the wrong bra size?

The 80% figure traces most directly to a small academic study of 30 women with self-reported back pain, plus internal fitting data from the UK retailer Marks & Spencer. The specific number shouldn't be treated as a precisely verified, universal statistic, but multiple independent studies do consistently find that a majority of women are not wearing an accurately sized bra.

What study is the source of the 80% bra size statistic?

The academic study most often cited is Breast size, bra fit and thoracic pain in young women: a correlational study, conducted at Victoria University in Melbourne, which found 80% of a 30-person sample of women aged 18-26 with self-reported back pain wore an incorrectly sized bra.

Why do so many women wear the wrong bra size?

The most common cause is a measuring methodology that either measures the band at the wrong point on the torso or adds extra inches to the raw measurement, producing a band size that doesn't match the person's actual rib cage.

Is there real evidence that bra fit problems are common, even if the 80% figure isn't precise?

Yes. A 2006 Harris Interactive study found 59% of women reported bra-related back, shoulder, or neck pain, and patent literature on bra-sizing methodology from the late 1990s independently describes a similar order of magnitude. Different studies, different populations, same general conclusion.

Find your accurate size with BRABAR's Fit Guide and Bra Size Calculator, built around the rib cage method rather than an added or relocated measurement.