Bra size chart & converter
Enter your underbust and bust measurements in centimetres and this converter returns the matching US/UK and EU band and cup size.
Result
- US / UK
- 34C
- EU / FR / IT / ES
- 75C
Band sizing follows the modern "band = nearest even underbust inch" method — an older +4in convention is still printed by some brands, which is the most common reason a self-measured size and a brand's own fitting differ.
Band size tracks the underbust measurement almost directly; cup size tracks the difference between bust and underbust, stepping up one letter per inch of difference. That’s the whole method behind both the US/UK and EU numbers this converter returns — the EU band number is simply a different scale (roughly underbust in centimetres, rounded to a multiple of 5) applied to the same underlying measurement.
The one place this method is least reliable is at the edges — a very small or very large difference between bust and underbust is where brands diverge most from the standard chart, which is exactly the situation an in-person fitting helps most with.
United Kingdom
UK sizing sits between the two systems most UK shoppers actually order from: US retailers (Amazon.com, US-only brands) and EU ones (Zalando, ASOS' EU warehouses since Brexit changed cross-border returns). A UK 6 shoe, a UK M ring and a UK 34C bra are each a different number again once the label says US or EU — which is why three-way conversion gets searched here more than in most single-market countries.
Every conversion on this page runs in your browser. Nothing you type is uploaded anywhere.
Frequently asked questions
Should I measure over or under my bust?
Underbust: snugly around the ribcage, directly under the bust. Bust: around the fullest part, with the tape level and not pulled tight. The difference between the two numbers is what determines the cup.
My measured size doesn't match what I usually wear — why?
Bra sizing varies more between brands than almost any other size chart on this site — a band and cup letter from one brand can differ by a full size from another. This chart gives the standard method's result, which is a starting point for trying a brand's own size guide, not a guarantee.
Why does the band size use even numbers only?
Bands are traditionally sold in even-numbered sizes (32, 34, 36...) in the US/UK system — this converter rounds a measured underbust to the nearest even number for that reason.
Last updated: 2026-09-10