A US J cup means your bust is about 10 inches bigger than your band, the same cup UK brands call GG. A UK J cup is three cups bigger, about 13 inches, which US labels would call M. So a “J cup” can mean two very different volumes depending on where the bra was made.
| Band 34 | Underbust over 32 and up to 34 inches (81–86 cm). We round your underbust up to the next even number. |
|---|---|
| Cup J | Bust about 10 inches bigger than the band: roughly 43½ to 44½ inches (110–113 cm) around the fullest part. |
| Sister sizes | 32K (UK 32H) (tighter band) and 36I (UK 36G) (looser band). Full diagonal: 28M (UK 28J), 30L (UK 30HH), 32K (UK 32H), 34J (UK 34GG), 36I (UK 36G), 38H (UK 38FF), 40G (UK 40F), 42DDD (UK 42E), 44DD, 46D, 48C. |
| Same size abroad | US 34J · UK 34GG · EU 75J · French 90J · Australia / NZ 12GG |
Brands measure differently, and some US brands add inches to the band. Use these numbers as a starting point, then check the fit. Calculate your own size · See every sister size · Convert another size
US J vs UK J
| Label | Cup difference | US equivalent | UK equivalent |
|---|---|---|---|
| US J | 10 in | J | GG |
| UK J | 13 in | M | J |
UK sizing runs D, DD, E, F, FF, G, GG, H, HH, J, JJ, K and skips I. US sizing usually runs D, DD, DDD, G, H, I, J, K. Our bra cup sizes in order guide shows every step.
US J cup sizes by band
| US size | UK size | Bust (approx. in) | Sister sizes (US) |
|---|---|---|---|
| 32J | 32GG | 42 | 30K, 34I |
| 34J | 34GG | 44 | 32K, 36I |
| 36J | 36GG | 46 | 34K, 38I |
| 38J | 38GG | 48 | 36K, 40I |
The underbust follows the band, as with every size: just over 32 up to 34 inches for a 34 band.
Where to find J cups
J cups are mostly made by brands that design for full busts, such as Elomi and Curvy Kate, and most of these use UK sizing. Curvy Kate’s US site lists sizes with both labels. Search by your UK size if a brand is UK-sized, and check the size chart before ordering.
What to look for in a J cup bra
- Seamed cups that are deep and wide enough at the base.
- Wide underwires that sit behind breast tissue at the sides.
- A deep band with three or more hooks.
- Wide or padded straps to spread the load.
- Side support panels that bring tissue forward.
Shop J cup bras
Affiliate links-
US J cup bras
The same cup as a UK GG.
Search Amazon for us j cup bras (opens in a new tab, affiliate link) -
UK GG cup bras
Full-bust brands often label in UK sizes.
Search Amazon for uk gg cup bras (opens in a new tab, affiliate link) -
J cup sports bras
Underwired, band-and-cup sized styles.
Search Amazon for j cup sports bras (opens in a new tab, affiliate link)
Results are Amazon’s, not our picks. Check the size range, the return policy and the features above before you buy.
How to know if you’re a J
Measure snugly under your bust (round up to the next even number) and loosely around the fullest part. 10 inches is a US J (UK GG); 13 inches is a UK J. The bra size calculator shows both, and our H cup and K cup guides cover the neighboring letters.
