International sizing feels confusing because brands often blend naming systems. The cleanest approach is to convert the band and cup separately, then compare that translated size with the brand's own size chart before buying.
Band systems follow local numbering logic
US and UK bands typically use even inch numbers like 32 or 34, while EU and JP commonly use centimeter-based bands such as 70 or 75. France and Spain usually add another numeric step, so the frame changes even when cup volume stays similar.
Cup progressions matter more than the letter alone
A UK FF is not the same label as a US FF in many retail charts. When you move into fuller-bust ranges, the order of doubled letters changes by system, which is why reading the sequence is safer than relying on one familiar letter.
Check brand-specific charts before checkout
Conversion tables are strong starting tools, but brands differ in stretch, depth, and how they label private-label production. Always compare your translated size with product reviews and return policies when trying a new maker.
Key takeaways
- Convert band and cup separately.
- Do not assume the same cup letters mean the same thing in every market.
- Use regional conversion as guidance, then confirm against the brand chart.
Reader note
This guide is intended for apparel fit education. Bra size labels vary by brand, and calculator results work best when paired with real fit feedback.