What Is Sizing Like at JJXX?

TELLAR FASHION HUB — SIZING GUIDE

By Ella Blake — Fashion Stylist | Tellar Fashion Hub — Always honest, unbiased & unsponsored

JJXX sizing runs small — particularly in jeans and fitted tops — and in most cases you'll want to size up at least one size from your usual, especially if you're between sizes or carry any curve through the hip and thigh.

JJXX — the womenswear arm of Danish denim giant Jack & Jones — launched in 2020 and has quietly become one of the more interesting affordable denim brands on the UK high street. The prices are great, the denim quality is genuinely decent, and the fits lean into that effortless, slightly-slouchy Scandi aesthetic I'm very much here for. But — and there is a but — sizing has been the brand's Achilles heel since day one, and if you don't know this going in, you'll end up frustrated with returns.

I'll be honest: the first time I picked up a pair of JJXX wide-leg jeans, I grabbed my usual size without thinking and they barely made it past my thighs. Not a great moment. Lesson learned. Size up, always.

JJXX JEANS: SIZE UP, NO QUESTION

Denim is where JJXX really excels, but it's also where the sizing quirks are most pronounced. The jeans use a waist/length system (W25–W34, with leg lengths in 30 and 32 inch inseams), which I actually love — it's far more precise than the standard UK 8/10/12 labelling. But the waist measurements come up small in practice.

Wide-leg & baggy fits — these have more room through the hip and thigh by design, but the waistband still runs tight. Size up one full size.
Straight-leg styles — the most consistent fit in the range, but still on the snugger side. If you're between sizes, go up.
Slim & skinny fits — noticeably small. Size up one, possibly two sizes if you have fuller hips or thighs. These are unforgiving.
Leg length — the 30" inseam works beautifully for petite to average heights (around 5'4"–5'7"), and the 32" is great for taller frames. They're among the better brands for catering to different heights at this price point.

💡 Stylist tip: If you're a UK 10 in most brands, start with a W28 in JJXX jeans. If you're between a 10 and 12, reach for W29 or W30. Don't be put off by the number — fit is everything.

TOPS, KNITWEAR & JACKETS: THE SAME STORY

The sizing-small issue extends beyond the denim. JJXX tops — from their graphic tees and linen shirts through to their knitwear and blouses — come up noticeably smaller than standard UK sizing.

T-shirts & casual tops — size up one. An XS from JJXX fits more like a children's 12–13 than an adult small. A UK 8–10 should be going for a Small or Medium.
Knitwear — this is where I'd actually say the oversized silhouettes work in your favour. Their chunkier knits and oversized jumpers are styled with extra room, so you can get away with your true size here for that relaxed look. But if you want a more fitted knit, size up.
Jackets & blazers — more consistent than the rest, but I'd still go one size up if you plan to layer underneath. The shoulder seams on their denim jackets can sit quite narrow.
Dresses — fit varies by style. Slip and wrap dresses generally run small; more structured shirt-style dresses are closer to true to size. When in doubt? Size up.

THE BRAND'S AESTHETIC — WHO IS JJXX FOR?

Understanding the aesthetic helps you shop smarter. JJXX is firmly in the relaxed, casual-cool camp — think slouchy wide-leg denim, oversized tees, linen shirting, and easy-wear dresses. It's not a brand for sharp tailoring or bodycon dressing. The whole vibe is effortless and slightly undone, which is honestly exactly what I want on weekends.

The price point sits comfortably in the affordable zone — comparable to ASOS own-brand or Mango basics — but the denim quality in particular punches above its weight. I've been genuinely impressed by how well some of their darker wash jeans hold their colour after washing. The fit for your money, once you've cracked the sizing, is really good.

The range also runs up to a UK 22 in some styles, which is better inclusivity than many brands at this price point, though some styles do drop off at a UK 18, so it's always worth checking individual listings.

MY QUICK VERDICT ON JJXX SIZING

✅ Size up one across almost the entire range
✅ Use the waist/length system for jeans — it's more reliable than trusting UK label sizes
✅ Oversized styles are the most forgiving and closest to true-to-size
⚠️ Slim-fit and skinny jeans can run up to two sizes small — approach with caution
⚠️ Sizing consistency varies by garment type, so check individual product reviews on ASOS before buying

WHERE TO SHOP INSTEAD — BRAND ALTERNATIVES BY BUDGET

If JJXX doesn't quite hit the mark for you — whether the sizing is frustrating or the aesthetic isn't quite your thing — here are my picks by budget, chosen specifically for brands that do relaxed denim and casual womenswear well.

HIGH STREET PICKS

River Island — excellent for denim in particular; their wide-leg and straight-leg styles are consistently well-cut and size more reliably than JJXX.
Mango — a strong JJXX alternative for the Scandi-casual aesthetic. Their linen and denim pieces have a very similar feel at a comparable price point.
Topshop (via ASOS) — still the benchmark for high street denim fit, especially straight and slim-leg styles. The sizing is more consistent.
Urban Outfitters — shares that relaxed, slightly streetwear-influenced DNA with JJXX. Good for baggy jeans, graphic tees and casualwear.
Abercrombie & Fitch — their denim has improved enormously in recent years. The Curve Love range is particularly good for fuller hips and thighs.
Hollister — great budget option for basics and denim; tends to size more true to standard UK labels than JJXX.
New Look — a solid budget pick for denim and casual tops, with a good size range and more predictable sizing.
All Saints — a step up in price but shares that relaxed, pared-back aesthetic beautifully, particularly for denim jackets and casualwear.

INDEPENDENT PICKS — A BIT LEFT-FIELD

Birdsong — a London-based ethical womenswear brand with a brilliant range of relaxed casuals and denim-adjacent pieces. Slow fashion, size-inclusive, and genuinely lovely quality. Worth a look if you like JJXX's vibe but want something more considered.
Nobody's Child — not strictly independent anymore but still under the radar compared to the big names. Their sustainable denim and casualwear has a very similar effortless aesthetic to JJXX, with more consistent sizing and better ethical credentials.

PREMIUM PICKS

Citizens of Humanity — if you want to invest in denim, this is where I'd point you. Their sizing is detailed, the fits are considered, and the denim quality is exceptional. Worth every penny.
Paige — another premium denim heavyweight. Particularly good for curvier figures; their Hoxton straight and Transcend fabric are game-changers for fit and comfort.

LUXURY & DESIGNER PICKS

Agolde — LA-based denim label that sits at the top of the casual-denim tree. Their 90s-fit and Riley crops are worn by everyone from off-duty models to stylists. Sizing is detailed and reliable.
Totême — for when you want that elevated, minimal Scandi aesthetic in premium denim and relaxed suiting. The price is significant, but the cut and quality are genuinely in a different league.

NEVER GET YOUR SIZE WRONG AGAIN

Sizing is genuinely all over the place across brands — and JJXX is a perfect example of why you can't rely on a label alone. That's exactly why I always recommend using Tellar.co.uk before you buy.

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