Polyester is the most widely used fibre in the world. It makes up 54% of all fibre produced globally — more than cotton, linen, wool, and silk combined. It's in your shirts, your dresses, your bedsheets, your gym clothes, and your coats.
It's also plastic. Made from petroleum. In an oil refinery.
Here's everything you need to know.
What Polyester Actually Is
Polyester's full chemical name is polyethylene terephthalate (PET) — the same plastic used to make water bottles, food containers, and industrial packaging. To turn it into fabric:
- Crude oil is refined into ethylene glycol and terephthalic acid
- These chemicals undergo a polymerisation reaction at high temperatures
- The resulting plastic is melted and forced through spinnerets — tiny holes that form it into fibres
- The fibres are drawn, crimped, and cut to mimic natural textile properties
- The synthetic fibres are spun into yarn and woven or knitted into fabric
The entire process happens in chemical plants. No farms, no fields, no growing season. That's why it's cheap — and why it dominates fast fashion.
Polyester by the Numbers
Why Polyester Dominates Fashion
In 1960, cotton represented 68% of global fibre production. Today it's about 24%. Polyester has taken over for one reason: it's cheap.
- Production cost — polyester costs roughly half as much as cotton to manufacture
- No agricultural dependency — no land, water, growing seasons, or weather risk
- Easy to manufacture — can be produced 24/7 in any climate, scaled instantly
- Wrinkle-resistant — looks crisp on hangers and in product photos
- Quick-drying — doesn't absorb water, so it dries fast
- Colour retention — holds dye well, doesn't fade as quickly
For fast fashion brands optimising profit margins, polyester is the obvious choice. It looks acceptable in product photos, costs almost nothing to produce, and most consumers don't check the label.
The Health Problem
Polyester creates several documented health issues:
Heat and Moisture Trapping
Polyester's dense, non-porous structure traps heat against your body and blocks natural ventilation. It absorbs almost no moisture (0.4% vs cotton's 27x its weight). Sweat sits on your skin instead of being absorbed — creating warm, wet conditions where bacteria thrive.
Bacterial Growth and Odour
Studies show polyester clothing harbours significantly more odour-causing bacteria than cotton. Micrococcus bacteria — the primary source of body odour — grow up to 3x faster on polyester than on cotton. This is why synthetic gym clothes smell worse and faster than cotton t-shirts.
Skin Irritation
While true allergies to polyester fibre are rare (under 1%), the chemical dyes and formaldehyde resins used in manufacturing cause contact dermatitis in up to 8% of sensitive populations. Dark-coloured synthetics are the worst offenders. Dermatologists consistently recommend natural fibres for eczema, dermatitis, and sensitive skin.
Microplastic Exposure
Microplastics from synthetic clothing have been found in human blood, lungs, and placenta. While research on health effects is ongoing, the presence of plastic particles in human tissue is a growing concern among toxicologists and public health researchers.
The Environmental Problem
- Microplastic pollution: Synthetic textiles are the largest source of microplastic pollution in the ocean. A single wash load releases up to 700,000 plastic fibres. These are too small for most treatment plants to capture.
- Decomposition: Polyester takes 20-200+ years to break down. A cotton t-shirt biodegrades in 1-5 months.
- Carbon footprint: Polyester production generates nearly 3x more CO₂ than cotton production per tonne of fibre.
- Non-renewable resource: Polyester is made from petroleum — a finite fossil fuel.
- Landfill: 85% of all textiles end up in landfill. Synthetic textiles will sit there for centuries.
What About Recycled Polyester?
Recycled polyester (rPET) is made from post-consumer plastic — typically PET bottles. It's a better starting point than virgin petroleum, but it doesn't solve the core problems:
- Still sheds microplastics — recycled polyester releases the same amount of microplastic fibres per wash as virgin polyester
- Still non-biodegradable — takes the same 20-200+ years to decompose
- Still traps heat and bacteria — same comfort and health drawbacks
- Mostly not recyclable again — textile-to-textile recycling is extremely limited. Most "recycled" polyester is bottle-to-textile, which is a one-way trip to landfill
Recycled polyester is better than virgin polyester. But it's still plastic clothing with the same problems for your body and the environment.
How to Spot Polyester in Clothing
Polyester hides behind many names and marketing tactics:
- On the label: Polyester, PET, polyethylene terephthalate, microfibre, "performance fabric"
- Blends to watch: "Cotton-rich" (often 40-60% polyester), "cotton blend," "mixed fibres"
- Marketing terms: "Wrinkle-free," "easy-care," "quick-dry" — often code for polyester content
- Visual clues: Unnaturally smooth sheen, plastic-like texture, extremely lightweight
The only reliable way to know is to check the fabric composition label — either on the garment itself, or on the product page when shopping online.
The Natural Alternatives
| Instead of Polyester | Try | Best For |
|---|---|---|
| Polyester t-shirt | 100% cotton | Everyday comfort, breathability |
| Polyester dress | Linen, silk, or viscose | Summer, formal, flowing fabrics |
| Polyester sweater | Merino wool or cashmere | Warmth, softness, durability |
| Polyester gym clothes | Merino wool or TENCEL | Anti-odour, temperature regulation |
| Polyester bedsheets | Cotton percale or linen | Sleep comfort, breathability |
| Polyester jacket | Wool, waxed cotton, or hemp | Outerwear that lasts |
How Much Polyester Is in Fast Fashion?
We've analysed over 17,000 products across major fashion retailers. Here's how much polyester they use:
Data from Fibr's analysis of 17,365 products. "Polyester-heavy" = 50%+ polyester by composition.