The Ultimate UK Clothing Size Guide: How Different Retailers Really Fit

Shopping for clothes online can be a minefield when it comes to sizing. If you've ever ordered your usual size 10 from different retailers only to find one fits like a glove while another won't zip up, you're not alone. The reality is that UK clothing sizes vary dramatically between retailers – and there's a good reason why.

Why UK Clothing Sizes Vary So Much

Here's something that might surprise you: there are no legal guidelines for clothing sizes in the UK. While most retailers loosely follow EU guidelines, they're free to use their own measurements. This means a size 12 dress from one store could have completely different measurements from a size 12 dress elsewhere.

Research has revealed that there can be up to 4 centimeters difference in measurements between the same labeled size across different stores. That's enough to make the difference between a perfect fit and an uncomfortable squeeze!

UK Retailers Size Comparison Chart

We've researched the major UK clothing retailers to create this comprehensive sizing guide. Use this chart to determine whether you should order your usual size, size up, or size down when shopping with different brands.

Quick Reference Chart

Retailer	Sizing Tendency	Recommendation	Notes
RUNS LARGE
Marks & Spencer	Large	Size down or stick to usual	Most generous fit overall
John Lewis	Large	Size down	Classic comfort fit
COS	Large	Size down	Scandinavian oversized aesthetic
TRUE TO SIZE
Next	True to size	Order usual size	Reliable for workwear & casual
ASOS	True to size	Order usual size	Consistent with UK standards
New Look	True to size	Order usual size	Slightly fitted but UK aligned
Tesco F&F	True to size	Order usual size	Standard UK sizing
ASDA George	True to size	Order usual size	Reliable UK sizing
Matalan	True to size	Order usual size	Follows UK standards
RUNS SMALL
Zara	Small	Size up	Narrow waist & hips, especially trousers
H&M	Small	Size up	Fitted tops run tight, especially Divided
Topshop	Small	Size up	Slim cuts, especially trousers & crops
River Island	Small	Size up	Slim fits around hips & legs
Boohoo	Small	Size up	Snug fits, especially partywear
PrettyLittleThing	Small	Size up	Tight across bust & hips
Missguided	Small	Size up	Generally runs small in fitted styles
Mango	Small	Size up	Continental fit - narrower cuts
& Other Stories	Small	Size up	European sizing standards
VARIABLE
Primark	Variable	Check individual items	Basics run large, trendy pieces fitted
TK Maxx	Variable	Check brand labels	Multiple brands, check measurements

Detailed Retailer Breakdown

The Generous Fitters

Marks & Spencer takes the crown for the most generous sizing across their range. Their approach focuses on comfort and classic styling, which means you'll often find their clothes roomier than expected. This is particularly true for their everyday wear and classic collections.

John Lewis follows a similar philosophy, designing for comfort rather than ultra-fitted fashion trends. Their house brands tend to be cut more generously, especially around the bust and waist.

COS reflects its Scandinavian heritage with deliberately oversized cuts, particularly noticeable in shoulders and chest measurements.

The Tight Fitters

Zara is notorious for running small, particularly in bottoms. Their European heritage shows in narrower hip and waist measurements. If you're between sizes, always size up with Zara.

H&M can be tricky – their basic items often fit true to size, but their trend-led pieces (especially the Divided line) run notably small. Their fitted tops are particularly tight across the bust.

Fast Fashion Favourites like Boohoo, PrettyLittleThing, and Missguided all trend toward smaller sizing. This reflects their target market's preference for body-conscious fits, but it means sizing up is often necessary for comfort.

The Reliable Ones

Next has built a reputation for consistent sizing, making them a safe bet for online shopping. Their measurements align well with standard UK sizing expectations.

ASOS maintains good consistency across their own-brand items, though remember they also stock other brands which may vary.

Pro Shopping Tips

Before You Buy

• Always check the size guide – even for brands you know well, as sizing can vary between different clothing lines
• Read the reviews – other customers often mention if items run large or small
• Consider the style – fitted and bodycon styles almost always run smaller than relaxed fits
• Measure yourself regularly – your measurements can change, and it's better to be certain

When in Doubt

• Between sizes? Check the brand's specific recommendation – many now advise whether to size up or down
• New brand? Start with your usual size but be prepared to exchange
• Special occasion? Order multiple sizes if the return policy allows it

Understanding Different Fits

Many retailers now offer different fit categories:

• Zara has TRF (younger, slimmer fit), Basic (true to size), and Woman (slightly roomier)
• ASOS clearly labels their fits as slim, regular, or oversized
• H&M distinguishes between their main line and Divided (which runs smaller)

The Bottom Line

Understanding how different UK retailers size their clothing can save you time, money, and the frustration of ill-fitting clothes. While sizing inconsistencies might seem annoying, they often reflect each brand's target customer and style philosophy.

The key is knowing what to expect from each retailer and adjusting your size selection accordingly. Keep this guide handy when shopping online, and remember – when in doubt, most UK retailers offer generous return policies, so you can always exchange for a better fit.

Happy shopping, and may all your online purchases fit perfectly!

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Remember: This guide is based on general sizing trends. Individual items may vary, so always check specific size charts and customer reviews when available.