What Size Am I in COS? A Technical Sizing Guide (UK & International)

COS (Collection of Style), owned by the H&M Group, is known for its minimal, architectural clothing and structured tailoring. But while its aesthetic is universal, its sizing can confuse shoppers—especially those transitioning from other UK high street brands.

Here’s a detailed, fact-based guide to how COS sizing works, what fits to expect, and how to find your exact size using Tellar.co.uk.

COS Sizing: What You Need to Know

1. General COS Sizing Characteristics

COS runs slightly large in many structured pieces like shirts, shirt dresses, and wide-leg trousers.
Their designs are intentionally oversized—not everything is meant to fit close to the body.
Silhouettes are unstructured or boxy, so even your usual size may feel roomier, especially if you have a petite or hourglass frame.

COS Size Conversion Chart (Women’s)

COS Label	UK Size	EU Size	US Size	Bust (cm)	Waist (cm)	Hip (cm)
32	4	32	0	76	60	84
34	6	34	2	80	64	88
36	8	36	4	84	68	92
38	10	38	6	88	72	96
40	12	40	8	92	76	100
42	14	42	10	96	80	104
44	16	44	12	100	84	108

COS rarely stocks above size 44/UK 16 in-store, though some extended sizes are online.

Fit Advice by Product Type

Tops & Shirts: Often oversized. If you’re in between sizes or prefer a neater fit, size down.
Shirt Dresses: Tailored but roomy through the waist. Use hip measurement as your guide.
Tailored Trousers: True to size. Check the waist closely—COS uses a straighter cut than curvy high-street brands.
Outerwear: Oversized by design. Many coats are dropped-shoulder or cocoon-style.
Knitwear: Looser fits with some stretch. Often suitable to size down depending on the look you want.

COS Sizing vs Other UK High Street Brands

Brand	How COS Compares
M&S	COS is roomier in fit, especially in dresses and coats.
Zara	COS fits larger and is better for taller or straight body types.
H&M	COS is more premium and structured with less cling and better tailoring.
Reiss	COS runs slightly larger, with looser tailoring and less emphasis on waist definition.
Arket	Very similar sizing (same parent company); cuts may be more architectural in COS.

How to Know Your COS Size Accurately – Without Guesswork

Instead of relying on trial and error—or buying multiple sizes—use Tellar.co.uk to instantly see your best-fitting size in COS based on your actual body measurements.

Here’s how it works:

Create a free profile at Tellar.co.uk.
Enter your bust, waist, and hip measurements, or your size in another brand you know fits you.
Use the Store Size Lookup tool and choose “COS”.
Instantly see the correct COS size for your body, along with comparisons to 1,500+ other brands.

No guesswork. No trial orders. Just accurate results.

Real Examples

If you’re a size 10 in M&S with a bust of 88cm and hips of 96cm, you’re likely a size 38 in COS—but for more tailored dresses, Tellar might recommend a 36 for a sharper fit.
If you wear a US 6 or UK 10 in Zara, Tellar may still recommend a 36 or 38 depending on your waist-to-hip ratio and COS product cut.

Tellar.co.uk: Smarter Sizing for COS and Beyond

COS is just one of over 1,500 brands supported by Tellar.co.uk. Whether you're shopping Reiss, Everlane, Arket, Massimo Dutti or Next—Tellar tells you your exact fit in seconds.

You’ll also find:

A fashion hub stacked with free style guides, fabric advice, and body shape recommendations.
No affiliate bias, no downloads, just real sizing science.
Always free to use.

➡️ Start with your free Tellar profile

➡️ Use the COS Store Size Lookup

➡️ Download the free printable measuring tape

Follow Tellar for COS Sizing & Styling Help

Instagram: @Tellarsizing
Twitter/X: @TellarSizing
Facebook: TellarSizing
Pinterest: TellarSizing

“Find your size in COS and 1,500+ brands real-time. It’s free & easy.”

COS Label	UK Size	EU Size	US Size	Bust (cm)	Waist (cm)	Hip (cm)
32	4	32	0	76	60	84
34	6	34	2	80	64	88
36	8	36	4	84	68	92
38	10	38	6	88	72	96
40	12	40	8	92	76	100
42	14	42	10	96	80	104
44	16	44	12	100	84	108

COS Label	UK Size	EU Size	US Size	Bust (cm)	Waist (cm)	Hip (cm)
32	4	32	0	76	60	84
34	6	34	2	80	64	88
36	8	36	4	84	68	92
38	10	38	6	88	72	96
40	12	40	8	92	76	100
42	14	42	10	96	80	104
44	16	44	12	100	84	108