40J bra size — conversion chart, sister sizes & brands
A 40J bra (US notation) in every regional standard. The same band-and-cup, labelled eight different ways.
| US | UK | EU | FR | IT | AU | JP | IN |
|---|---|---|---|---|---|---|---|
| 40J | 40GG | 90J | 105J | 90J | 18GG | 90J | 40GG |
Band conversions are exact; cup fit still varies by brand, style, and body — a conversion is a starting point, not a guarantee.
Sister sizes of 40J
Sister sizes hold the same cup volume with a different band — the quickest fix when a band feels too tight or too loose.
Not sure you're a 40J? Two measurements, two minutes — free, nothing stored.
Check my size →Brands that make J-cup bras
40J FAQ
- What is 40J in EU sizing?
- 40J (US) is EU 90J. In UK sizing it is 40GG. Band conversions are exact; cup fit still varies by brand, style, and body — a conversion is a starting point, not a guarantee.
- What are the sister sizes of 40J?
- 42I — same cup volume, different band.
- Is 40J the same in every brand?
- No. A 40J can fit differently between brands because of pattern, fabric and cup shape. Use it as a starting point and try a sister size when switching brands.