30J Bras

A 30J means a 30-inch band with a J cup — roughly a 13-inch difference between your underbust and your bust measurement. Cup letters are not consistent between markets: UK-sized brands like Panache run a different ladder to US labels, so your 30J may sit a letter along depending on who made it.

How a 30J should fit

A 30J is a full-bust size, and the engineering matters more than the label. Wide side wings, a firm band with four hooks and seamed cups will outperform a prettier bra with thin straps every time.

Sister sizes to try if 30J isn't right

• Band feels loose but the cup is right — try 28JJ
• Band is comfortable but you're spilling over — go up to 30JJ
• Band digs in — 32HH gives the same cup volume with more room

Best 30J styles

Look for side support panels, which push tissue forward and stop it migrating under the arm — the single most useful feature at 30J. Full cup and balconette shapes both work; strapless is harder at this size and worth trying with a longline style, which spreads the weight across a wider band.