Which High Street Brands Run Large and Which Run Small? A Complete UK Sizing Breakdown

Shopping for clothes on the UK high street can be deceptively complex. Two garments, both marked “UK 10”, can fit completely differently depending on the brand. While size labels suggest standardisation, the reality is anything but. Most brands apply their own fit model, manufacturing tolerances, and vanity sizing policies—leading to significant inconsistency.

This guide explores which UK high street brands tend to run large or small, why these discrepancies exist, and how Tellar.co.uk solves the issue by matching your measurements to the correct size across over 1,500 brands.

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Why Brand Sizes Vary So Much

Before we list which brands run large or small, it’s important to understand why this happens. Brand sizing is not regulated by any universal standard in the UK or EU. Instead, brands use a mix of:

• Proprietary fit models (based on specific body shapes, often hourglass or athletic)

• Target demographic preferences (younger brands may fit smaller; comfort-driven brands may cut roomier)

• Fabric and stretch variations (jeans vs. viscose dresses behave very differently)

• Vanity sizing (intentionally labeling a size 12 as a 10 to appeal to customer psychology)

Even within the same brand, a “UK 10” may vary significantly depending on fabric, style, or collection.

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High Street Brands That Typically Run Small

These brands are often more trend-led, younger-targeted, or European in origin. Their cuts are slimmer, tighter across the chest, hips, or waist, and may feel undersized compared to typical UK expectations.

1. Zara

• Origin: Spain

• Known for: Trend-driven styles, narrow cuts, limited stretch

• Fit notes: Zara consistently runs small across most categories, especially in trousers, blazers, and fitted dresses. Many shoppers size up one or two sizes.

2. H&M (Divided Line)

• Origin: Sweden

• Known for: Affordable fashion, trend-led younger styles

• Fit notes: H&M sizing varies, but the Divided collection (aimed at teens/young adults) typically runs small, particularly in tops and fitted skirts.

3. Bershka / Stradivarius

• Origin: Spain (Inditex group, like Zara)

• Known for: Youth fashion, fast trends, slim tailoring

• Fit notes: These brands run 1–2 sizes smaller than UK standards, especially in denim and jackets. Inseams also tend to be shorter.

4. Mango

• Origin: Spain

• Known for: Chic, minimalist pieces with European sizing

• Fit notes: Mango is known to run slim across the shoulders and bust, particularly in dresses and blazers. Size up if in between.

5. Urban Outfitters

• Origin: US, but UK sizing often differs

• Known for: Bohemian and street styles

• Fit notes: Many of their in-house labels run small, especially in structured or fitted garments like corsets or cropped trousers.

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High Street Brands That Typically Run Large

Brands targeting a broader UK demographic, prioritising comfort, or aiming for looser silhouettes often run large or oversized—especially in knitwear, outerwear, and dresses.

1. Marks & Spencer (M&S)

• Origin: UK

• Known for: Quality basics, wide demographic, classic silhouettes

• Fit notes: M&S tends to run generous, especially in jersey, knitwear, and loose-fit dresses. Some styles are intentionally oversized. Many customers size down in casualwear.

2. Monsoon

• Origin: UK

• Known for: Occasionwear, relaxed tailoring, boho-inspired styles

• Fit notes: Many Monsoon dresses and tops run large through the bust and waist, and can feel loose on petite frames.

3. White Stuff

• Origin: UK

• Known for: Relaxed, countryside-inspired casualwear

• Fit notes: Cuts are generally roomy, particularly in knitwear, tunics, and trousers. If you’re between sizes, sizing down is often advised.

4. FatFace

• Origin: UK

• Known for: Coastal-casual styles, relaxed fit clothing

• Fit notes: Most garments run large, particularly in the chest and hip area. Great for layering, but can be baggy if not sized correctly.

5. Seasalt Cornwall

• Origin: UK

• Known for: Sustainable, practical, coastal-inspired fashion

• Fit notes: Consistently generous fits, especially in linen dresses and smocks. Size down for a more tailored silhouette.

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Brands with Inconsistent Sizing Across Categories

Some brands are difficult to place because their fit changes based on garment type, collection, or fabric:

1. H&M (Mainline)

• In tops: Often true to size

• In trousers/denim: Often runs small

• In outerwear: May run large or oversized by design

2. River Island

• Sizing can fluctuate depending on fabric and style. Fitted dresses and trousers tend to run small, while casualwear (like t-shirts or oversized shirts) may run large.

3. ASOS

• ASOS carries both in-house brands and third-party labels.

• ASOS Design: Often runs true to size or slightly large

• ASOS Petite: Runs small

• ASOS Tall: True to size but longer proportions

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Size Conversion Table: UK vs Actual Fit Tendency

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Why This Matters: The Impact of Incorrect Sizing

Getting your size wrong isn’t just inconvenient—it has real implications:

• Returns contribute to waste: In the UK, over 30% of online fashion purchases are returned. Many are never resold.

• Poor fit reduces garment lifespan: Clothes that are too tight lose structure; oversized pieces may stretch or be underworn.

• Customer frustration reduces brand trust: Shoppers are less likely to re-purchase if sizing is unpredictable.

That’s why tools like Tellar.co.uk are essential for modern shoppers.

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Tellar.co.uk: Your Personal Size Matching Tool

Rather than guessing or relying on inconsistent labels, Tellar.co.uk gives you brand-specific size recommendations based on your body measurements. It’s completely free to use and takes less than two minutes to set up.

Features include:

• ✅ Printable measuring tape for bust, waist, and hips

• ✅ Profile setup to store your sizes

• ✅ Real-time brand lookup tool

• ✅ Conversion between UK, US, and EU sizing

• ✅ Works in cm or inches

Instead of asking “Should I size up in Zara?”, Tellar gives you a tailored answer: “For your bust and waist, Zara recommends a UK 12 in this dress.”

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Final Thoughts: Smart Shopping Starts with Fit

In the UK high street, size tags are best treated as guidelines—not absolutes. The variation between brands, and even within collections, can make sizing feel arbitrary.

Instead of relying on trial-and-error or brand myths, consumers now have access to data-driven solutions.

With Tellar.co.uk, you can shop smarter, waste less, and buy with confidence—knowing your size is tailored to both your body and the brand you’re buying from.

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Ready to Find Your True Fit?

📐 Download Tellar’s free measuring tape

👤 Create your profile

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