Thread Report · 875 products analyzed · Updated July 28, 2026

What is COS made of?

Better than most. COS averages 78.2% natural fibre, which puts them ahead of many competitors. But not everything is equal.

According to Fibr's Thread Report (July 2026), 9% of COS's 875 analysed products are majority-synthetic, with an average natural-fibre content of 78.2%.

875Products Analyzed
78.2%Avg Natural Fibre
9%Polyester-Heavy
55.8%Nearly All-Natural

COS's sweaters are 98.9% natural fibre, but their skirts are just 64.2%. That's a 35-point gap — where you shop within COS matters as much as whether you shop there at all.

The full picture on COS.

COS is one of the stronger performers in our dataset, averaging 78.2% natural fibre across 875 products we analyzed. Only 9% of products are polyester-heavy — relatively low compared to many retailers. On the bright side, 55.8% of COS products are made almost entirely from natural fibres (95%+). The most common fibre across COS products is Cotton, appearing in 45.3% of items.

How Products Break Down

875Products

  • Synthetic

    <30% natural fibre · 83 products

    9.5%

  • Blend

    30–85% natural fibre · 278 products

    31.8%

  • Natural

    85–100% natural fibre · 514 products

    58.7%

Most Common Fibres (% of products containing)

Cotton
45.3%
Wool
20.1%
Elastane
15.9%
Polyester
15.3%
Polyamide
14.3%

Where to buy (and avoid).

Not all categories at COSare equal. Here's where the natural fibres are.

Safe Zones · 70%+ natural

Sweater98.9% natural · 29 productsJeans98.2% natural · 116 productsT-Shirt94% natural · 62 productsShirt87.3% natural · 82 productsShorts86.2% natural · 36 productsPants86.1% natural · 73 productsCoat76.4% natural · 69 products

Mixed Bag · 40–70% natural

Dress67.6% natural · 217 productsJacket67% natural · 72 productsBlazer64.9% natural · 38 productsSkirt64.2% natural · 41 products

What we found.

Across 875 products analyzed, COS averages 78.2% natural fibre content.

9% of COS products are majority polyester — that's 79 items made mostly from plastic.

COS sweaters are their strongest category at 98.9% natural fibre (29 products).

Their weakest category: skirts at just 64.2% natural (41 products).

Only 55.8% of products (488 items) are 95%+ natural fibre.

All categories ranked by natural fibre percentage
CategoryProductsAvg Natural %
Sweater2998.9%
Jeans11698.2%
T-Shirt6294%
Shirt8287.3%
Shorts3686.2%
Pants7386.1%
Coat6976.4%
Dress21767.6%
Jacket7267%
Blazer3864.9%
Skirt4164.2%

Sample Products

A selection of COS products from our database — from most natural to most synthetic. Click to view on the retailer's site.

CLEAN CUT REGULAR LONG-SLEEVED T-SHIRT100% Natural
CLEAN CUT REGULAR LONG-SLEEVED T-SHIRT
Cotton 100%
REGULAR DOUBLE-BREASTED WOOL BLAZER100% Natural
REGULAR DOUBLE-BREASTED WOOL BLAZER
Wool 100%
TIDE WIDE-LEG JEANS100% Natural
TIDE WIDE-LEG JEANS
Cotton 100%
TIDE WIDE-LEG JEANS100% Natural
TIDE WIDE-LEG JEANS
Cotton 100%
LOOSE-FIT CROPPED JUMPER84% Mixed
LOOSE-FIT CROPPED JUMPER
Wool 51%Alpaca 33%Polyamide 16%
MERINO WOOL BUTTONED SHIFT MINI DRESS84% Mixed
MERINO WOOL BUTTONED SHIFT MINI DRESS
Wool 52%Cotton 32%Polyester 16%
MERINO WOOL BUTTONED SHIFT MINI DRESS84% Mixed
MERINO WOOL BUTTONED SHIFT MINI DRESS
Wool 52%Cotton 32%Polyester 16%
PLEATED WIDE-LEG DENIM TROUSERS84% Mixed
PLEATED WIDE-LEG DENIM TROUSERS
Cotton 68%Lyocell 32%
FLARED KNITTED MINI DRESS29% Synthetic
FLARED KNITTED MINI DRESS
Viscose 58%Polyamide 41%Elastane 1%
FLARED KNITTED MINI DRESS29% Synthetic
FLARED KNITTED MINI DRESS
Viscose 58%Polyamide 41%Elastane 1%
KNITTED PEPLUM TOP29% Synthetic
KNITTED PEPLUM TOP
Viscose 58%Polyamide 41%Elastane 1%
TWO-TONE CHUNKY KNITTED TANK TOP27% Synthetic
TWO-TONE CHUNKY KNITTED TANK TOP
Polyester 68%Cotton 27%Polyamide 5%

The verdict.

COS is one of the better options for natural fabrics. With 55.8% of products being nearly all-natural, you have real choices here. Still — always check the label. Not every item is created equal.

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Frequently asked questions.

What is COS clothing made of?

Based on our analysis of 875 COS products, the average garment is 78.2% natural fibre. The most common single fibre is Cotton (in 45.3% of products). The remaining material is typically synthetic — polyester, polyamide, or acrylic.

Is COS cotton?

Sometimes — cotton appears in 45.3% of the 875 COS products we analyzed, but it's usually blended with synthetics. Only 55.8% of items are nearly all-natural (95%+ natural fibre), so check the composition before assuming a piece is pure cotton.

Is COS 100% cotton?

Some pieces are. Of the 875 COS products we analyzed, 245 are 100% cotton (or near-pure, 95%+) — that's 28.0% of the catalog. The rest are blends.

How much polyester does COS use?

9% of COS products are polyester-heavy, meaning polyester makes up 50% or more of the garment. This is below average for fast fashion retailers.

Is COS mostly synthetic?

9% of COS products are polyester-heavy (50%+ polyester). Average natural fibre content is 78.2%, so the rest of the catalog is mostly natural-led.

Does COS use natural fabrics?

55.8% of COS products are nearly all-natural (95%+ natural fibre). A decent portion of their range avoids synthetic fibres entirely.

Is COS sustainable in terms of fabric?

Fabric composition is one factor in sustainability. With an average of 78.2% natural fibre, COS is better than many competitors on this measure. Natural fibres generally biodegrade and shed fewer microplastics than synthetics.

Methodology: We analyzed 875 COSproduct pages, extracting the fabric composition listed by the retailer. Products are categorized by name keywords. Natural fibre percentage is the sum of all natural fibres (cotton, linen, silk, wool, viscose, lyocell, etc.) in each product's composition. Data is refreshed monthly.

Use this data.

The Thread Report is openly licensed. Cite it, download it, query it directly — just link back to the source page.

Last updated
License
Free to cite with attribution
Raw dataset (JSON)
info.tryfibr.app/cos.json ↓
Computed stats (JSON)
/api/thread-report/cos
About the dataset
How it's built & how to cite it
LLM index
/llms.txt

Suggested citation

Fibr Thread Report — COS, 2026-07-28. tryfibr.app/thread-report/cos

Related reports.

Is COS Sustainable?What the fabric data says — and what it can'tCOS T-Shirt62 products, 94% naturalCOS Blazer38 products, 64.9% naturalCOS Sweater29 products, 98.9% naturalCOS Coat69 products, 76.4% naturalPolyester at COSIn 15.3% of productsCotton at COSIn 45.3% of productsElastane at COSIn 15.9% of productsCOS vs Abercrombie & Fitch78.2% vs 73.7% naturalCOS vs Acne Studios78.2% vs 78.4% naturalBrand rankingsSee where every brand lands on natural fibreAbout the Thread ReportHow the dataset is built, and how to cite it

Explore the Thread Report

Part of an openly-licensed dataset.

This page is one view of Fibr's Thread Report — fabric composition data for major fashion retailers, free to read and cite. Explore the rest:

About the Thread ReportWhat the dataset is, how it's built, and how to cite it.All brand reportsFabric breakdowns for every retailer we track.Brand rankingsWho uses the most natural fibre — and the most polyester.Brand comparisonsHead-to-head fabric data for every viable brand pair.Research findingsOriginal findings built on the dataset.State of FabricThe annual report on fashion's fibre mix.MethodologyHow we classify fibres and compute every number.Fabric guides & researchHow to read labels, decode fibres, shop smarter.

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