Do 80% of Women Wear the Wrong Bra Size?

Where the numbers come from

You will see the claim as 70%, 80% or 85%, usually with no source. Three studies are most often behind it.

What these studies can and cannot tell us

They are small

Thirty, forty-five and a hundred or so participants. That is enough to show a pattern exists. It is not enough to put a reliable percentage on a whole population.

They are not representative

Two of the three recruited women with a specific problem: those seeking breast reduction, and those with back pain. People in those groups may be more likely than average to be in a poorly fitting bra. The results cannot simply be extended to everyone.

"Wrong" depends on the yardstick

Each study compared what women wore with a size chosen by a trained assessor using fit criteria. Fit is partly a matter of judgement, and a different assessor might draw the line slightly differently.

The third study measured a method

The Portsmouth figures of 76% and 84% describe how often the traditional tape-measure formula disagreed with a professionally fitted size. That is a finding about a sizing method. It is often quoted as if it were a count of women in the wrong bra, which it is not.

What is reasonably well supported

• Many women wear a bra that does not fit well. Every study that has looked has found a high proportion, and fitters say the same.
• The usual error has a direction. Band too big, cup too small. The Portsmouth study showed the traditional method produces exactly that, and found it grew worse as band size increased.
• Women with larger breasts are most affected. The 2008 study found they were particularly likely to be in an incorrectly sized bra, and the 2003 study was of women with large breasts.
• Being taught to judge fit helps more than being given a size. That was the Portsmouth authors' recommendation.

What is not established

• A precise national percentage. No large, representative study has measured one.
• That a wrong bra size causes back pain. The 2008 study, which is the source of the 80% figure, found only negligible relationships between pain and bra fit. See back pain and the wrong bra size.

Why the figure spread

It is memorable, it sounds scientific, and it is useful to anyone selling bras or fittings. Retailers and magazines have repeated it for years, often citing their own customer surveys, which are not research. A statistic that makes most readers think "that could be me" travels well.

A better question than "am I in the 80%?"

Whether you personally are in a well-fitting bra takes about a minute to find out.

1. Look side-on. Is the band level, or higher at the back?
2. Press the centre panel. Is it flat on your breastbone?
3. After a scoop and swoop, is there any bulge over the cups?
4. Slip the straps off. Does the bra stay up?

If any of those fail, signs your bra doesn't fit will tell you what to change. If they all pass, you can ignore the statistic.

Frequently asked questions

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

The figure does appear in a small 2008 Australian study, and other small studies have found similar or higher proportions. None was a representative sample of all women, so "80%" should be read as "a large share, in the groups studied", not as a measured national figure.

What is the most common bra sizing mistake?

A band that is too big paired with a cup that is too small. A University of Portsmouth study found the traditional measuring method overestimated band size in 76% of participants and underestimated cup size in 84%.

How do I know if I am wearing the wrong size?

Check the fit, not the label. If the band rides up at the back, the centre panel does not sit flat, or tissue bulges over the cups, the size is off.