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Parfait Lingerie
Casey Full Bust Padded Plunge T-Shirt Bra - Dark Blue Denim
$37.80$54.00Unit price /Unavailable-
Parfait Lingerie
Mia Wire-Free Full Bust Padded Bralette - Blackberry
$39.20$56.00Unit price /Unavailable-
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Parfait Lingerie
Mia Wire-Free Full Bust Lace Bralette - Cork
$50.40$56.00Unit price /Unavailable-
Parfait Lingerie
Charlene Underwire Full Bust Padded Bra - Warm Sand
$59.00Unit price /Unavailable-
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Parfait Lingerie
Emily Full Busted Unlined Non-Padded Wired T-Shirt Bra - Warm Sand
$55.00Unit price /Unavailable-
Parfait Lingerie
Adriana Wire-Free Full Bust Supportive Bralette - Blackberry
$49.50$55.00Unit price /Unavailable-
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Parfait Lingerie
Casey Full Bust Padded Plunge T-Shirt Bra - Mosaic Black
$38.50$55.00Unit price /Unavailable-
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Parfait Lingerie
Shea Full Bust Longline Strapless Bra - Racing Red
$46.20$66.00Unit price /Unavailable-
Parfait Lingerie
Shea Full Bust Longline Strapless Bra - Black
$46.20$66.00Unit price /Unavailable-
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Parfait Lingerie
Mia Wire-Free Full Bust Lace Bralette - Bare
$39.20$56.00Unit price /Unavailable-
Parfait Lingerie
Shea Full Bust Unlined Plunge Bra - Racing Red
$50.40$56.00Unit price /Unavailable-
Parfait Lingerie
Shea Full Bust Unlined Plunge Bra - Petal Pink
$39.20$56.00Unit price /Unavailable-
Parfait Lingerie
Charlotte Full Bust Padded Longline Bra - Racing Red Dot
$39.20$56.00Unit price /Unavailable-
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Parfait Lingerie
Adriana Wire-Free Full Bust Supportive Bralette - Bare
$55.00Unit price /Unavailable-
Parfait Lingerie
Charlotte Full Bust Lace Unlined Bra - Sapphire
$36.40$52.00Unit price /Unavailable-
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J Cup Bras: The UK J, Fitted and Explained
J is a UK full-bust cup near the top of the ladder — one step above HH, roughly a 13-inch difference between bust and band. It's a specialist size, cut almost entirely by UK houses like Panache, Cleo, Elomi and Sculptresse, and at this volume fit is decided by construction, not the letter.
Below: where J sits on the UK ladder, what it converts to in US and EU sizing, how sister sizing widens your options, and which styles actually hold at this cup instead of collapsing under the volume.
What is a J cup?
J is a UK-system full-bust cup — one step above HH, roughly a 13-inch bust-to-band difference. In the extended single-letter system US full-bust retailers use, it converts to a US M (EU M), though almost every brand that makes this size labels it UK-style. The letter is relative to the band — a 30J and a 40J aren't the same volume. Shop J cup bras in balconette, full-cup, sports and strapless styles, bands 28 to 44.
How to choose a J cup bra
At this cup, construction does the work the letter can't. Five things separate all-day support from a bra you fight by noon.
| What to check | What good looks like | Why it matters |
|---|---|---|
| The band | Firm and level all the way around, snug on the loosest hook, barely a finger under it | At J the band carries most of the weight — a loose or riding band throws the load onto the straps and the cup fails |
| Cup construction | Four or more seamed sections rather than a single moulded piece | Seaming is what shapes and lifts real volume; a one-piece moulded cup flattens and loses projection at this size |
| Side support panels | Firm panels inside the side of the cup, pushing tissue forward | They stop breast tissue migrating toward the underarm — the single biggest fit issue at J and above |
| Straps & hooks | Wide, cushioned, fully adjustable straps and four hooks or more | Narrow straps dig and can't distribute the weight; more hooks give the band the tension it needs |
| Underwire | Tall, wide wires that sit flat in the crease and fully encircle the breast root | A wire that's too narrow rides onto tissue and digs; at J the root is wide and the wire has to match it |
J vs. HH vs. JJ: UK, US & EU
Where J sits, and what the same cup is called in each system.
| UK cup | Bust − band | US equivalent | EU equivalent |
|---|---|---|---|
| H | ~11 inches | K | K |
| HH | ~12 inches | L | L |
| J | ~13 inches | M | M |
| JJ | ~14 inches | N | N |
Why does UK use J where US uses M? The UK ladder doubles some letters (G, GG, H, HH, J, JJ) as it climbs, while the US full-bust system runs a single continuous alphabet (…L, M, N, O). They count the same cup volumes — a UK J and a US M are the same cup — they just label the rungs differently. Note that UK skips the letter I to avoid confusion with the numeral, so HH is followed directly by J. Nearly every bra made at this size is a UK-labelled full-bust brand (Panache, Cleo, Elomi, Sculptresse), so you'll almost always be shopping the UK letter. The practical takeaway: trust the band-plus-cup fit, not the letter. If you're converting up from an HH that spills, J is the next stop; the cup below is our HH cup edit, the cup above is JJ.
Find your J cup bra
Pick the card that matches what you need it to do — then tap through to shop.
Balconette & full cup
Side-support panels and a tall wire are what hold a J forward and up. Full-cup shapes contain the most.
Shop full figure →Everyday t-shirt bra
Smooth-lined but seam-supported cups — the good ones at J hide seams under the fabric without losing structure.
Shop t-shirt bras →Sports bra for a J cup
Encapsulation with a hook back and firm side panels — a compression shelf can't control bounce at this volume.
Shop sports bras →Converting up from HH?
If your HH cup spills at the top or under the arm and the band is right, J is the next cup. See the HH edit to compare.
Shop HH cup →Need the cup above?
If a J still spills with the band snug, the next stop is JJ (US N). The JJ edit is the same fit logic, one cup up.
Shop JJ cup →Not sure it's your size?
UK, US and EU all label this cup differently. Run your size through the converter to be certain.
Convert my size →At J, a bra lives or dies on its construction. The letter tells you the volume; the seams, the side panels and the wire tell you whether it will actually hold.
The HauteFlair StandardThe complete J cup sizing guide
How UK cups climb, what J converts to, sister sizing, fit checks and the vocabulary.
01How to measure for a J cup at home+
Two measurements, one subtraction. Take them in a non-padded bra or none at all:
- Band: measure snugly around your ribcage directly under the bust, keeping the tape level and parallel to the floor.
- Bust: measure loosely around the fullest part, without compressing.
- Subtract band from bust. Each inch of difference is roughly one cup — about 13 inches lands in UK J territory (a US M).
At this size the number is only a starting point. Breast shape, root width and how the volume distributes matter more than the tape, and brand cut varies. Use the fit checks below to confirm.
02Why UK, US and EU disagree at this cup+
The systems count the same volumes but label the rungs differently once you climb past DD:
- UK sizing: doubles letters as it rises and skips I — …GG, H, HH, J, JJ, K. J is one step above HH. Nearly all full-bust brands (Panache, Cleo, Elomi, Sculptresse) use this.
- US full-bust: runs a single continuous alphabet — …L, M, N. A UK J is a US M.
- EU: also single continuous alphabet, so EU M matches the US letter here.
Because the size is made almost exclusively by UK houses, you'll usually be shopping the UK letter directly. The US and EU equivalents matter mainly when a chart or retailer lists them.
03Sister sizing, and how to use it+
Cup volume stays roughly constant if you move the band and the cup in opposite directions:
- Band too tight? Go up a band and down a cup — 34J → 36HH holds about the same volume.
- Band too loose? Go down a band and up a cup — 34J → 32JJ.
- What it doesn't fix: a cup that's the wrong shape for you. Sister sizing moves volume; it can't change projection or wire width.
At J, sister sizing is especially useful because the size is made by fewer brands — widening your options by a band in each direction can be the difference between finding the style you want and not. The full logic is in our sister sizes guide.
04The five-second fit check+
Do this in front of a mirror, in profile, wearing the bra on the loosest hook:
- Band level? If it rides up in back, size down a band — at J a firm band is non-negotiable.
- Gore tacking? If it floats off your sternum, the cup is too small.
- Any spill? Over the top or under the arm means go up a cup — not down a band.
- Any gaping? Empty space at the cup edge means go down a cup.
- Wires in the crease? If they rest on tissue or sit narrow, the wire isn't matched to your root.
Scoop and swoop first — lean forward and settle everything into the cup — then judge. At this volume, tissue that never got into the cup is the most common cause of a "wrong size" verdict.
05J cup, full figure, plus size: the vocabulary+
- J cup — a UK-system cup one step above HH; the same cup US full-bust retailers call M.
- Full figure — a cut, not a size. Full-figure bras are built for large cups at any band: heavy seaming, side panels, wide straps, more hooks. Nearly all J bras are cut this way.
- Plus size — about the band, not the cup. A 30J is a very large cup on a small band and isn't plus size at all.
- Side support — internal panels that push tissue forward and stop it migrating under the arm. Essential at J.
- Encapsulation vs. compression — sports bra terms. Encapsulation gives each breast its own cup; compression flattens against the chest. At J, only encapsulation works.
J cup bras FAQ
The questions shoppers ask most, answered straight.
What is a J cup size?
J is a UK-system full-bust cup, one step above HH, corresponding to roughly a 13-inch difference between your bust and band measurements. In the extended single-letter system US full-bust retailers use it converts to a US M. It's a relative letter, not a fixed volume: a 30J and a 40J share a label but hold very different amounts, because the cup is always measured against the band.
What is a J cup in US sizing?
A UK J is a US M. The UK ladder doubles letters as it climbs and skips I (H, HH, J), while the US full-bust system runs a single continuous alphabet (L, M, N), so the same cup lands on M. In practice almost every bra made at this size is a UK-labelled brand, so you'll usually shop the J letter directly.
Is a J cup bigger than an HH?
Yes — one UK cup bigger, at the same band. A 34J has more cup volume than a 34HH. But a 30J is smaller than a 36HH, because the band changes what the letter means. This is why comparing cup letters across different bands tells you almost nothing.
What cup size comes after J?
In UK sizing, JJ — the ladder runs HH, J, JJ, K. A UK JJ is a US N. If a J is spilling but the band is level and snug, JJ is the next cup up.
Which brands make J cup bras?
J is a UK full-bust specialty, so the brands that make it are the UK houses: Panache and its Cleo and Sports lines, Elomi, Fantasie and Sculptresse. They build for the size with seamed cups, side support panels, wide straps and firm bands — the construction a cup this size needs.
How do I measure for a J cup bra?
Measure snugly under your bust for the band and loosely around the fullest part for the bust, then subtract. Roughly an inch per cup, with about 13 inches landing in UK J range (US M). Treat it as a starting point — at this size, breast shape, root width and brand cut move the answer, so the mirror check matters more than the tape.
Is a J cup considered plus size?
No — plus size describes the band, and J describes the cup. A 30J is a very large cup on a small frame. What J bras almost always are is "full figure," which is a cut built for large cups at any band: heavy seaming, side support panels, wider straps and more hooks. See our full figure edit.
What is sister sizing for a J cup?
Sister sizes hold roughly the same cup volume on a different band. Going up a band means going down a cup: 34J sisters to 36HH. Going down a band means going up a cup: 34J sisters to 32JJ. It's especially useful at J, where fewer brands make the size — sistering widens the styles available to you.
Why does my J cup bra gape at the top?
Gaping usually means the cup is too large or the wrong shape — not that you need a tighter band. Scoop everything into the cup first; if space remains at the edge, go down a cup. A seamed, side-supported cup handles asymmetry and shape variation far better than a rigid moulded one at this volume.
What's the best sports bra for a J cup?
An encapsulation style with a hook-and-eye back, wide adjustable straps and firm side panels — a compression shelf can't control bounce at J. Panache's underwired sports bras are cut to this size range specifically. See our sports bras.
Sizing guidance here is general and reflects how UK, US and EU cup letters typically translate; charts, cut and cup shape vary by brand, so always check the size chart for the specific bra you're buying. Size availability reflects current stock. Last reviewed August 2026.
Shop J cup bras
UK J support — a US M — in balconette, full-cup, sports and strapless styles, built for the cup with the seaming, side support and firm bands the size needs.
