UK vs USA Clothing Sizes: The Complete Sizing Conversion Guide for Women

Author: Tellar Stylist Team

Published: July 2025

Disclaimer: This post is honest, independent, and written by the Tellar.co.uk editorial team. No brand pays for placement.

When shopping internationally, one of the most confusing challenges is understanding clothing sizes—especially the difference between UK and US sizing. A UK size 10 isn’t the same as a US 10, and this discrepancy can lead to frustrating returns, sizing errors, and ill-fitting clothes. This guide explains everything you need to know to convert UK and US sizes accurately, plus how Tellar.co.uk can do it for you instantly.

1. Key Differences Between UK and US Clothing Sizes

The primary difference is numeric. US sizes are typically two sizes lower than the equivalent UK size. So, for example:

UK Size	US Size Equivalent
UK 4	US 0
UK 6	US 2
UK 8	US 4
UK 10	US 6
UK 12	US 8
UK 14	US 10
UK 16	US 12
UK 18	US 14

This applies to most women’s clothing: dresses, skirts, tops, jackets, and suits. However, fit still varies by brand, and body measurements (bust, waist, hips) don’t always translate cleanly between the two systems.

2. What’s the Reason for the Difference?

The UK and US developed independent sizing systems. British sizing was historically based on actual body measurements in inches, later standardised into size numbers. American sizing used similar foundations but evolved with different grading rules and consumer expectations.

For instance:

US brands often vanity size more aggressively—meaning a size 8 may fit like a UK 12.
UK brands tend to keep sizing more rigid, though this is changing.

3. Bust, Waist, and Hip Comparison Table

Here’s a rough body measurement conversion chart by bust-waist-hip to clarify how sizes align:

UK Size	Bust (cm)	Waist (cm)	Hips (cm)	US Size
UK 4	76–78	58–60	84–86	US 0
UK 6	78–81	61–63	86–89	US 2
UK 8	82–85	64–66	90–93	US 4
UK 10	86–89	67–70	94–97	US 6
UK 12	90–93	71–74	98–101	US 8
UK 14	94–97	75–78	102–105	US 10
UK 16	98–102	79–83	106–110	US 12

This chart is a guideline only. Different brands, especially across the US and UK, interpret these sizes differently.

4. Designer vs High-Street Sizing

US Designers (like Reformation, Michael Kors, Theory):

Tend to run smaller than UK High Street brands.
A US size 6 in these brands may feel more like a UK 8-10.

UK High Street (like M&S, River Island, Whistles):

Offer more generous sizing.
A UK 10 can often feel like a US 8.

For luxury or boutique brands, always consult real-time sizing tools like Tellar.co.uk before you buy.

5. Sizing by Garment Type

Tops and Dresses: Stick to the two-size difference rule.
Trousers and Jeans: Waist measurements often use inches in both UK and US—double check inseams too.
Shoes: Totally different system (UK 5 = US 7.5 in women’s shoes).
Lingerie: Bra sizing systems are not interchangeable—band and cup sizes differ entirely.

6. How UK and US Sizes Compare to Europe

European sizes use an entirely different system. Generally, a UK 10 / US 6 = EU 38. If you want full breakdowns, see:

👉 UK vs USA vs European Clothing Sizes: The Ultimate Guide

7. Why You Can’t Trust Size Labels Alone

A UK size 10 from COS will not fit the same as a UK 10 from Zara. Even within the UK, and especially across borders, brands grade sizes differently. Factors affecting this include:

Fit model body proportions (often based on country of origin)
Market expectation (e.g. tighter tailoring vs relaxed fits)
Fabric stretch and construction

That’s why size conversion charts should be treated as starting points, not guarantees.

8. How to Convert Your Size Accurately (Without Charts)

Instead of guessing:

Measure your bust, waist and hips in cm or inches.
Know your usual size in at least one known brand.
Use Tellar.co.uk’s Store Size Lookup Tool to get your exact size across 1,500+ UK and US brands instantly.

No more conversions. No more mistakes.

🧠 What is Tellar.co.uk?

Tellar.co.uk is the UK’s Leading Sizing Tool, created to match your body to real brand size data across COS, Reiss, Everlane, Arket, and more.

It removes the need to convert UK/US/EU sizes manually.

How It Works:

✅ Measure once using bust, waist, and hip

✅ Or enter your usual size in any known brand

✅ Use the Store Size Lookup Tool

✅ Get your best-fitting size across thousands of brands

✅ Shop confidently—fewer returns, better fit

No downloads. No cost. Works in-browser.

🛠 Bonus Tools from Tellar:

📏 Free Printable Measuring Tape

➡️ Create Your Free Tellar Profile

📚 Fashion Hub Access: Honest, independent advice on thousands of fashion topics, including:

⚠️ Common UK to US Sizing Mistakes

Mistake 1: Assuming a UK 10 is the same as US 10 (wrong—it’s US 6).
Mistake 2: Using brand charts without real measurement data.
Mistake 3: Forgetting to check fit type (slim, classic, oversized).
Mistake 4: Trusting only the size label on international orders.
Mistake 5: Assuming all US brands vanity size (some don’t).

📊 Summary Chart – Fast UK to US Size Reference

UK	US
4	0
6	2
8	4
10	6
12	8
14	10
16	12
18	14

💬 Final Thought

If you’re shopping from both UK and US brands, size conversion is essential—but it’s not as simple as subtracting 2. The most reliable way to find your fit is by using actual body data and real-world brand measurements. That’s exactly what Tellar.co.uk offers.

Skip the confusion. Know your size. Shop smart.

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