Cotton On is one of Australia’s most recognisable fashion retailers, offering affordable everyday wear across womenswear, menswear, activewear, and loungewear. Known for its accessible price point and laid-back aesthetic, it’s popular with UK shoppers looking for easy wardrobe staples. But despite its global appeal, many customers in the UK find Cotton On sizing confusing, especially when ordering online.
If you’re unsure whether to size up, down, or stick with your usual UK number, this guide is here to help. Below, you’ll find conversion charts, real fit advice from UK shoppers, and tips for navigating Cotton On’s most popular product categories. And for total confidence, you can match your body measurements to Cotton On’s sizing directly at Tellar.co.uk—free, fast, and based on real fit data.
Is Cotton On True to Size?
Cotton On uses Australian sizing, which typically runs slightly smaller than UK high street brands, particularly in womenswear. The cuts often cater to a slimmer fit through the hips, waist, and bust, especially in bodycon or structured items.
Based on user insights from Tellar.co.uk, here’s how Cotton On sizing usually performs for UK customers:
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Tops & T-shirts – Generally true to size, with a relaxed or boxy fit
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Jeans & Trousers – Often run small at the waist and hips; size up for comfort
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Dresses – Fit depends on the material—structured styles tend to be snug, while jersey and ribbed options stretch more
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Swimwear – Comes up small, especially in the bust. Many UK shoppers size up.
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Loungewear & Cotton On Body (underwear) – True to size or slightly generous, depending on the style
The best way to get an accurate size match is to use your own measurements. Create your free profile on Tellar and we’ll instantly match your fit across Cotton On and more than 1,500 brands.
Cotton On Size Conversion Chart – UK to AU/US
As an Australian brand, Cotton On uses AU sizing by default. Here’s how that converts for UK shoppers:
| UK Size | AU Size | US Size |
|---|---|---|
| 6 | 6 | 2 |
| 8 | 8 | 4 |
| 10 | 10 | 6 |
| 12 | 12 | 8 |
| 14 | 14 | 10 |
| 16 | 16 | 12 |
Cotton On often lists sizes as XS to XL on product pages as well:
| Alpha Size | UK Equivalent |
|---|---|
| XS | 6–8 |
| S | 8–10 |
| M | 10–12 |
| L | 12–14 |
| XL | 14–16 |
Important: Stretch, fabric type and product category all affect how the size feels. That’s why Tellar’s sizing system is more accurate—it uses your bust, waist and hip measurements to give exact brand-to-body matches.
Popular Cotton On Categories – Fit Advice
1. Cotton On Jeans
Styles like the “Straight Leg”, “90s Baggy” or “Mom Jean” are popular for their affordability and on-trend silhouettes. However, they tend to run small at the waistband.
UK Fit Insight: If you’re between sizes or curvier in the hips, size up. The waist often sits high and the fabric has little stretch.
2. Cotton On Body (Loungewear & Underwear)
Cotton On Body offers soft, relaxed basics in ribbed and cotton fabrics, including bras, leggings, and shorts.
UK Fit Insight: Most pieces are true to size. Sports bras and bralettes tend to suit A–C cups best; DD+ wearers may need to size up or opt for styles with adjustable support.
3. Dresses
From jersey midis to printed tea dresses, Cotton On’s dresses vary in cut and stretch.
UK Fit Insight: Ribbed and jersey styles are flexible and forgiving. Structured styles (like wrap or button dresses) often fit tightly at the waist—size up if you’re between sizes.
4. Swimwear
Stylish but often lacking support, Cotton On swim tends to run small across the bust and hips.
UK Fit Insight: Size up if you have a fuller bust or want more coverage. The designs suit smaller cup sizes better.
How to Measure Yourself for Cotton On
Because Cotton On sizing can differ between categories, measuring yourself properly is key.
Here’s what to measure:
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Bust – Around the fullest part of your chest
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Waist – Narrowest point between ribs and hips
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Hips – Around the widest part of your bum and upper thighs
Once you’ve measured, you can enter your details at Tellar.co.uk to see your most accurate Cotton On size, as well as sizing in hundreds of other brands.
Don’t have a measuring tape? Tellar will even post you one for free.
Where to Buy Cotton On in the UK
Cotton On ships internationally via its main website, and is occasionally stocked through:
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Cottonon.com (AU/global site)
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ASOS (UK) – Carries select seasonal styles
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Zalando – Offers Cotton On pieces with UK returns
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The Iconic – Ships internationally (note: returns may be more complex from the UK)
Tip: Before placing an order, check your Cotton On size using Tellar’s size lookup to avoid cross-border returns or shipping costs.
UK Customer Reviews – What Real Shoppers Are Saying
“The jeans were tight on the waist, but the leg fit perfectly. I had to return my usual size 10 and re-order a 12.”
— Emma, Sheffield
“I love the crop tops and basics—they’re true to size, but I always use Tellar now to double-check.”
— Keisha, London
“The swimwear looks amazing but is definitely made for smaller cup sizes. I size up and still get a flattering fit.”
— Hannah, Bristol
Why Tellar.co.uk Works Best for Cotton On
Unlike static size charts, Tellar.co.uk uses real measurements to tell you exactly which size you’ll need—not just for Cotton On, but for over 1,500 other brands too.
Tellar:
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Matches your bust, waist and hips to real-world fit data
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Converts between UK, AU, US and EU sizing automatically
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Stores your profile for faster shopping across multiple retailers
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Helps reduce returns by getting the fit right the first time
It’s accurate, completely free, and built to work across high street, designer, and emerging labels alike.
Explore More Fit Guides Like This
If you’re shopping at Cotton On, you may also be interested in:
Each guide uses the same real-data approach to give you trustworthy sizing info in seconds.
Find Your Cotton On Size in Seconds with Tellar
Tired of guessing your size, returning items, or getting inconsistent fits? Tellar.co.uk is the tool UK shoppers trust to get it right the first time.
Whether you’re shopping basics, jeans, swimwear or loungewear, you can get your exact Cotton On size in under a minute—just by entering your measurements once.
Start now at Tellar.co.uk and simplify sizing forever.
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