Every garment sold in the United States is required by law to have a fiber content label. Most people glance at it and move on. Knowing how to actually read it — what the percentages mean, what the fiber names tell you, and what the label leaves out — changes how you shop.
Where to Find Fiber Content
In the United States, the Textile Fiber Products Identification Act requires all garments to include a label listing fiber content by percentage, the country of manufacture, and the manufacturer’s name or RN (Registered Number). This label is typically sewn into the collar, side seam, or waistband.
Some brands have moved to “tagless” printing directly on the interior of the garment — the same information is required; it’s just printed rather than sewn.
For garments sold online, fiber content is required to be listed on the product page. This is the same information as the physical label.
How to Decode Common Materials
The label lists fibers from highest to lowest percentage. Here’s what the most common names mean:
Cotton: Natural plant fiber. Soft, breathable, absorbent. “Cotton” alone on a label doesn’t specify conventional or organic — look for GOTS certification for organic cotton assurance.
Polyester: Synthetic petroleum-derived polymer. Durable, moisture-wicking, wrinkle-resistant. Sheds microplastics during washing.
Nylon: Synthetic polymer, often used for strength and stretch in outerwear, swimwear, and activewear. Also sheds microplastics.
Wool: Natural protein fiber from sheep. “Wool” can mean many grades — merino (fine, soft), Shetland (medium, textured), or commodity wool (coarser). The label won’t tell you the micron count.
Merino Wool: Fine-grade wool, typically listed separately from generic “wool” when the brand wants to signal quality. Softer and higher-performing than standard wool.
Linen: Natural fiber from flax. Breathable, durable, slightly textured. Gets softer with washing.
Silk: Natural protein fiber, smooth and lightweight. May be listed as “silk” or by specific type (charmeuse, habotai, chiffon — these are weave types, not separate fibers).
Spandex / Elastane / Lycra®: Synthetic elastic fiber. Usually present in small percentages (2–10%) to add stretch. Lycra® is DuPont’s brand name for elastane.
Rayon / Viscose: Semi-synthetic fiber made from cellulose (usually wood pulp). Soft and drapey. Requires significant chemical processing — look for OEKO-TEX® certification.
Modal: A type of rayon made specifically from beech wood pulp. Softer than standard rayon. OEKO-TEX® certification is meaningful here.
Tencel® / Lyocell: Semi-synthetic made from wood pulp (often eucalyptus) in a more closed-loop process than standard viscose. Generally considered lower-impact processing.
Acrylic: Synthetic wool substitute. Soft but sheds significantly more microplastics than most synthetics. Common in sweaters and fleece.
What Blends Can Tell You
A blended fabric has two or more fibers. The percentages tell you what’s dominant and what’s supplemental.
High natural fiber content (70%+): The garment’s performance and feel will be largely determined by that natural fiber. A 72% cotton / 25% polyester / 3% spandex t-shirt will feel mostly like cotton.
Small synthetic percentage (2–5%): Usually spandex for stretch. Doesn’t significantly change the feel or chemical profile of the primary fiber.
Higher synthetic percentage (30–50%): Meaningfully affects performance (durability, moisture management, price) and the garment’s microplastic shedding during washing.
Equal parts blend: A 50/50 cotton/polyester blend exhibits properties of both. Wrinkles less than pure cotton; breathes better than pure polyester.
When evaluating blends, consider: what purpose does each fiber serve? A small polyester percentage in a linen shirt is typically for durability; a 50% polyester content is more likely a cost driver.
What Labels Don’t Tell You
The fiber content label is required by law — but it doesn’t tell you everything:
Chemical finishes: PFAS coatings, stain-resistant treatments, wrinkle-free resins, and antimicrobial treatments are applied to the fabric after it’s formed and aren’t reflected in fiber content.
Dye chemistry: The label doesn’t specify which dye class was used.
Fiber quality: “Wool” can mean coarse or fine. “Cotton” can mean short-staple commodity cotton or long-staple premium cotton. The label doesn’t indicate quality grade.
Country of fiber origin vs. manufacturing: “Made in Portugal” refers to where the garment was assembled, not necessarily where the fiber was grown or the fabric woven.
Certification status: The label won’t tell you if it’s GOTS or OEKO-TEX® certified — that’s found on hangtags, brand websites, or certification databases.
FAQ
What does “other fibers” mean on a label?
Labels can list “other fibers” for any component under 5% if that’s accurate. This is legal but limits visibility. Ask the brand if you want specifics.
Why does “bamboo” on a label say “viscose” in parentheses?
The FTC requires that bamboo-derived fabric be labeled with its actual fiber name: viscose (or rayon) from bamboo. “Bamboo fabric” alone is a marketing term; viscose/rayon is what the fiber legally is after processing.
Does a higher cotton percentage always mean better quality?
Not necessarily. A 100% cotton t-shirt in cheap commodity cotton isn’t better than a 95% organic cotton / 5% spandex in long-staple organic. Percentage tells you composition; certification and brand transparency tell you more about quality.
What’s the difference between Lyocell and Tencel®?
Tencel® is Lenzing AG’s brand name for their lyocell fiber. All Tencel® is lyocell; not all lyocell is Tencel®. Tencel® carries additional claims about production process; generic lyocell doesn’t.
Related reading: How to Read Clothing Labels · Sustainable Fabric Blends Explained
Check labels with Wove. Download Wove for iPhone or Android and get an instant fiber and chemical grade on any garment — no label decoding required.
Sources
- U.S. Federal Trade Commission: Textile Fiber Products Identification Act
- GOTS: Certification Database
- OEKO-TEX®: STANDARD 100 Overview
- Lenzing AG: Tencel® and Modal Fiber Information