📊 Why 80% of Women Wear the Wrong Bra Size

Studies from the UK and US show that around 80% of women wear the wrong bra size. Here is why — and how to fix it for free at home.

A 2008 study published in the Chiropractic & Osteopathy journal measured 102 women and found that 80% were wearing the wrong size. A larger 2024 fit-industry survey put the number at 75–85%. The pattern is consistent across countries and decades.

The two biggest reasons

First, the outdated "+4" measurement formula taught in many books and online. Second, the assumption that going up a band is the same as going up a cup. Neither is true.

How to fix it

Use a modern method: round your under-bust to the nearest even number (no plus-four). Subtract under-bust from bust to get cup. Try the calculated size on the loosest band hook.