Why Do Clothing Sizes Vary So Much Between Brands? Here's the Real Reason (and How to Fix It)

Ever tried on three different sizes in the same shopping trip? Or ordered your “usual” size online only to find it’s too tight, too loose, or just wrong? You're not alone. Brand sizing is inconsistent—wildly so. A UK 12 in one store can fit like a UK 10 in another, and sometimes even like a 14. It's not your body that's the problem. It's the system.

In this post, we’ll unpack why sizing differs so much across brands, what’s really behind the chaos, and how tools like Tellar.co.uk are putting an end to the guesswork—once and for all.

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The Fashion Industry’s Best-Kept Secret: There Are No Standard Sizes

That’s right. Despite what the labels say, there’s no universal rulebook for clothing sizes. Each brand defines their own size charts based on:

• Their ideal customer demographic

• Internal design and fit preferences

• Their chosen “fit model” (a real person with specific body proportions)

So when Zara, White Stuff, and Whistles all sell clothes in UK sizes 6–18, they’re actually using totally different base measurements. It’s no wonder your “usual size” feels anything but consistent.

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Vanity Sizing: Making You Feel Good (While Making Things Worse)

Here’s where things get even more complicated. Many brands deliberately label garments with smaller sizes than their true measurements—a practice known as vanity sizing. It’s meant to make customers feel better about themselves. But it wreaks havoc on consistency.

Take these examples:

• A UK 12 at M&S could fit the same as a UK 14 at H&M

• Premium fashion brands often cut smaller to maintain a sleek, tailored aesthetic

• Fast fashion brands may size down to appeal to a younger demographic

So if you've ever worn a 10, 12, and 14 in the same week—you weren’t imagining it. You’re just shopping in a broken system.

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UK, US, EU... Which Size Am I?

International conversions are a whole other minefield. In theory:

• A UK 12 should equal a US 8 and an EU 40

But in practice?

• Massimo Dutti, Maje, and Sandro (all European) tend to run small

• US brands like J.Crew or Abercrombie often run large

Even when brands offer size conversion charts, they rarely reflect the actual fit of the clothing. Add to that style differences and fabric variations, and it becomes nearly impossible to buy confidently without trying something on.

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Size Charts: Helpful or Hopeless?

Most brands provide a size chart. And yes, they can be useful—if you have accurate measurements, and if you understand what you’re looking at.

But here’s the catch:

• Many shoppers don’t own a measuring tape

• Even fewer know how to measure correctly

• Size chart definitions can be vague (e.g. “waist” could mean natural waist or garment waistband)

Plus, one brand might define a Medium as 28" waist, while another defines it as 30". Within the same store, tops, jeans, and dresses may all be cut to different specifications.

That’s not just confusing—it’s exhausting.

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Fabric, Cut & Style Matter Too

Sizing doesn’t just come down to numbers. The fabric and style of a garment play a huge role in how it fits.

So that size 12 blazer from Reiss might feel snug, while a size 12 viscose blouse from COS drapes loosely—even if they're the same size on paper.

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High Street vs Luxury: Different Brands, Different Goals

Let’s break it down:

Each brand builds their sizing philosophy around their market position. That means there’s no “standard” way to shop—unless you rely on your own body measurements, and even then, interpreting them across brands can be a nightmare.

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The Solution: Tellar.co.uk

That’s where Tellar.co.uk comes in. It’s the UK’s leading free size matching tool, designed to eliminate the guesswork by using your actual measurements, not vague size labels.

Instead of switching between 10 brand websites and size charts, Tellar does the work for you.

✅ Create Your Personal Size Profile

Input your bust, waist, and hips once—and Tellar instantly tells you your size in over 1,500 brands, from high street to designer.

It only takes a one-time login to access everything—completely free.

👉 Create your profile now

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✅ No Measuring Tape? No Problem.

If you don’t know your measurements, Tellar offers a free printable measuring tape you can download and use at home.

Just print, cut, and measure—it’s that easy.

👉 Download your free measuring tape

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✅ Built for UK Shoppers

Tellar is made specifically for UK consumers. It factors in:

• Whether a brand runs small, large, or true to size

• Differences between tops, bottoms, and dresses

• Material stretch and fit style

You won’t just get a size—you’ll get context. Like:

"This brand’s trousers run small in the waist, but true to size in the hips.”

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How Tellar.co.uk Compares to Other Sizing Tools

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Real-Life Problems. Solved.

“I’m a size 12 in M&S but a 14 in H&M. What gives?”

Tellar shows your correct fit across both—based on your body.

“I’ve stopped buying online—it’s too hit and miss.”

Tellar removes the guesswork, helping reduce returns.

“I don’t know my size in French or American brands.”

Tellar has you covered with real-world UK, EU, and US size translations.

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Get Started in 3 Easy Steps

1. Go to www.tellar.co.uk

2. Create your profile (manually or with the free printable tape)

3. Search your favourite brand—and find your best size instantly

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Final Thoughts: You Deserve a Sizing System That Works

Clothing size inconsistency isn’t your fault. It's the result of outdated standards, inconsistent fit models, and marketing-driven sizing strategies. But with Tellar.co.uk, you can take the guesswork out of shopping—and finally feel confident in every purchase.

Stop guessing. Start knowing.

👉 Find your size at Tellar.co.uk today

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