Every piece of clothing is made from one of two things: something that was grown, or something that was manufactured in a chemical plant.
Natural fibres come from plants and animals — cotton, linen, wool, silk, hemp, cashmere. Synthetic fibres are made from petroleum — polyester, nylon, acrylic, elastane.
Today, synthetic fibres make up 69% of all fibres produced globally. Polyester alone accounts for 54%. This guide covers every dimension of the comparison: comfort, health, environment, cost, durability, and performance.
The Complete Comparison Table
| Property | Natural Fibres | Synthetic Fibres |
|---|---|---|
| Source | Plants and animals | Petroleum (oil refineries) |
| Breathability | Excellent — air passes through fibre structure | Poor — dense, non-porous structure traps heat |
| Moisture absorption | High (cotton: 27x its weight, wool: 30%) | Almost none (polyester: 0.4%) |
| Skin health | Hypoallergenic, dermatologist-recommended | Can cause rashes, acne, irritation |
| Odour | Minimal bacterial growth | Bacteria grow 3x faster; retains odour |
| Microplastics | None | Sheds 700,000+ fibres per wash |
| Biodegrades | Weeks to months | 20-200+ years |
| CO₂ footprint | Lower (cotton: ~5kg CO₂/kg) | Higher (polyester: ~14kg CO₂/kg) |
| Cost | Higher (requires agriculture) | Lower (petrochemical process) |
| Wrinkle resistance | Lower (linen wrinkles most) | High — holds shape well |
| Drying speed | Slower (absorbs water) | Fast (repels water) |
| Colour retention | Good, fades naturally over time | Excellent, holds dye longer |
| Chemical treatments | Fewer (especially organic) | More (formaldehyde, disperse dyes, finishing agents) |
| Recyclability | Easier (especially 100% compositions) | Difficult (especially blends) |
The Natural Fibres
Cotton
The world's most popular natural fibre. Soft, breathable, absorbent, hypoallergenic. Makes up ~24% of global fibre production. Used in everything from t-shirts to bed sheets. Organic cotton (GOTS certified) carries the fewest chemical residues of any commercial fabric.
- Best for: Everyday basics, sensitive skin, underwear, baby clothes, bedding
- Limitations: Wrinkles, can shrink, slower to dry
Linen
Made from flax. The oldest textile in history (36,000+ years). Stronger than cotton, more breathable, gets softer with every wash. Lasts 10-20 years.
- Best for: Summer clothing, hot climates, bedding, high-durability items
- Limitations: Wrinkles heavily, higher price point
Wool
Animal fibre from sheep. Naturally temperature-regulating — warm in winter, cool in summer. Absorbs up to 30% of its weight in moisture without feeling wet. Naturally antibacterial, odour-resistant, and flame-retardant.
- Best for: Sweaters, coats, suits, base layers, socks
- Limitations: Some people react to lanolin, can felt if washed incorrectly
Silk
Produced by silkworms. The finest natural fibre, with a characteristic lustre and smooth hand-feel. Clinical evidence shows silk reduces eczema severity by 30%. Naturally temperature-regulating and hypoallergenic.
- Best for: Sensitive skin, sleepwear, luxury clothing, linings
- Limitations: Expensive, delicate, requires careful washing
Hemp
One of the most sustainable fibres. Requires minimal water, no pesticides, and actually improves soil quality. Stronger than cotton, naturally antimicrobial, and softens with wear.
- Best for: Durable clothing, denim, casual wear, sustainability-focused wardrobes
- Limitations: Can feel coarse initially, limited availability
Cashmere
Ultra-fine wool from cashmere goats. Exceptionally soft, lightweight, and warm — 3x more insulating than sheep's wool. However, up to 90% of "cashmere" products on the market are fake or heavily diluted with cheaper fibres.
- Best for: Luxury knitwear, scarves, premium layering
- Limitations: Expensive, widely counterfeited, environmental concerns with overproduction
The Semi-Synthetic Fibres
These sit between natural and synthetic — made from natural sources (wood pulp) but through chemical processing:
- Viscose / Rayon — chemically processed wood pulp. Soft and drapey but production uses toxic solvents (carbon disulfide). Breathes better than polyester but worse than cotton.
- TENCEL / Lyocell — similar to viscose but produced in a closed-loop system that recycles 99% of solvents. Exceptionally smooth, breathable, and dermatologist-recommended for sensitive skin.
- Modal — beech wood pulp, processed similarly to viscose. Softer than cotton, good moisture management. Often blended with cotton for underwear and loungewear.
- Bamboo — usually bamboo viscose (chemically processed). Soft and antibacterial but the production process raises environmental concerns. Mechanically processed bamboo linen is better but rare.
The Synthetic Fibres
Polyester (PET)
The most produced fibre on Earth — 54% of global fibre production. Made from petroleum. Cheap, wrinkle-resistant, quick-drying. Also non-breathable, odour-retaining, microplastic-shedding, and potentially irritating to skin.
- Used because: It's cheap. Half the cost of cotton to produce.
- Problems: Heat trapping, bacteria growth, microplastic shedding, 200+ year decomposition, chemical treatments
Nylon (Polyamide)
The first fully synthetic fibre (invented 1935). Strong, elastic, abrasion-resistant. Common in activewear, swimwear, hosiery, and outerwear.
- Used because: Durability and stretch. Better moisture management than polyester but still synthetic.
- Problems: Non-biodegradable, non-breathable, similar health concerns to polyester
Acrylic
A cheap substitute for wool. Soft, lightweight, warm — but entirely synthetic. The least breathable common fabric and the highest microplastic shedder.
- Used because: It mimics wool at a fraction of the cost. Common in cheap sweaters and blankets.
- Problems: Worst breathability, highest microplastic shedding, pills easily, loses shape
Elastane (Spandex / Lycra)
Stretch fibre found in almost every modern garment. Always blended — never used alone. Stretches up to 600% and returns to shape.
- Used because: No natural fibre offers comparable stretch. 2-5% elastane makes any fabric more comfortable.
- Problems: Makes garments harder to recycle, not breathable in high percentages
Comfort Comparison
Natural fibres are objectively more comfortable in most conditions. They breathe, absorb moisture, and regulate temperature naturally. Synthetics trap heat, repel moisture (leaving it on your skin), and provide a warm, damp environment for bacteria.
The exception: very high-intensity exercise in wet conditions, where synthetic fabrics' quick-drying property offers a genuine advantage. Even here, merino wool and TENCEL are increasingly competitive.
Health Comparison
The health evidence consistently favours natural fibres:
- Skin conditions: 60-70% of eczema sufferers report worse symptoms with synthetics. Dermatologists universally recommend natural fibres.
- Allergies: Disperse dyes in synthetics cause contact dermatitis in up to 8% of sensitive populations. Formaldehyde resins in "wrinkle-free" synthetics are a known allergen.
- Microplastics: Synthetic fibres shed plastic particles found in human blood (77% of samples), lungs, placenta, and breast milk. Natural fibres shed biodegradable particles.
- Chemical load: Synthetic fabrics require more chemical processing. Natural fibres (especially organic) carry fewer residual chemicals.
Environmental Comparison
| Impact | Natural | Synthetic |
|---|---|---|
| Carbon footprint | ~5 kg CO₂/kg (cotton) | ~14 kg CO₂/kg (polyester) |
| Decomposition | Weeks to months | 20-200+ years |
| Microplastics | None (biodegradable fibres) | 700,000+ per wash load |
| Water use | Higher (agriculture) | Lower (industrial) |
| Land use | Requires farmland | None (factory-produced) |
| Recyclability | Good (especially 100% compositions) | Limited (especially blends) |
| Resource | Renewable (plants regrow) | Non-renewable (petroleum) |
Natural fibres have a smaller carbon footprint, biodegrade at end-of-life, and don't pollute waterways with microplastics. Their main environmental drawback is higher water and land use — though organic farming practices and more efficient irrigation are improving this.
Cost Comparison
Synthetic fibres are cheaper upfront — that's the entire reason they dominate fast fashion. But the cost equation changes when you factor in longevity:
- A quality linen shirt lasting 15 years at £80 = £5.33/year
- A polyester shirt lasting 3 years at £20 = £6.67/year (and you need to buy 5 to cover the same period)
Natural fibres also retain resale value better — a well-maintained wool coat or cotton denim jacket holds value in secondhand markets. Synthetic garments lose value almost immediately.
When Synthetics Make Sense
To be fair, there are specific use cases where synthetics offer genuine advantages:
- Waterproof outerwear — though waxed cotton and treated wool are natural alternatives
- Extreme-performance athletics — though merino and TENCEL are closing the gap
- Stretch garments — small amounts of elastane (2-5%) provide stretch no natural fibre can match
- Very tight budgets — synthetics are genuinely cheaper
For the other 80-90% of your wardrobe — t-shirts, shirts, trousers, dresses, underwear, sleepwear, bedding — natural fibres are better in almost every dimension.
How Much Synthetic Fabric Is in Fast Fashion?
We analysed 17,365 products across major retailers. The results show that even brands perceived as "quality" have significant synthetic content:
Data from Fibr's analysis of 17,365 products across 6 retailers, 2026.
No major retailer sells exclusively natural fibres. The only way to ensure you're buying natural is to check each product's composition individually.