How to Read a Clothing Fiber Content Label

Almost every piece of clothing sold in the United States has a small label listing what it is made of. Those labels follow federal rules, and once you know the rules, the label tells you a lot in very few words.

The following is a summary of what a fiber content label has to show, how to read it, and how certification labels differ from it.

---

The Rules Behind the Label

In the U.S., fiber content labels are required by the Textile Fiber Products Identification Act and the Wool Products Labeling Act, and the Federal Trade Commission (FTC) sets out the details. A clothing label must show the fiber content, the country where the garment was made, and either the name of the company that made or sold it or its Registered Identification Number (RN), a number the FTC issues.¹

Care instructions are covered by a separate FTC rule, the Care Labeling Rule, which is why the care symbols are often on their own label.²

---

Reading the Fiber Content

Percentages by Weight

Fibers are listed by their percentage of the fabric’s weight, in order from the largest share to the smallest.¹ “60% cotton, 40% polyester” means 60% of the fabric’s weight is cotton. Because percentages are by weight, a lightweight fiber can take up more of the fabric than its percentage suggests.

Generic Names

Labels must use the generic name of each fiber, the name of the fiber type rather than a brand. A trademark may appear, as in “Lycra spandex” or “TENCEL lyocell,” but the generic name has to appear with it.¹ Some generic names differ by country, and the FTC also recognizes the international (ISO) names, so a U.S. label can say elastane instead of spandex, and viscose instead of rayon.¹

“Other Fiber”

A fiber that makes up less than 5% of the weight is listed as “other fiber” instead of by name, unless it has a definite function at that amount.¹ That is why a small amount of spandex is usually named, since it adds stretch, while a few decorative threads may just be “other fiber.”

Tolerance and “100%”

Percentages can be off by up to three percentage points, so a label that says 40% cotton may be anywhere from 37% to 43%.¹ There is no tolerance for a single-fiber claim. A label that says “100%” or “all” of one fiber means just that, although some decorative trim and ornamentation can be excluded.¹

---

Garments with More Than One Fabric

When a garment has sections made of different fibers, the label identifies each section separately,¹ for example “Body: 100% cotton. Lining: 100% polyester.” Linings used for warmth must be disclosed, while linings used only for structure don’t have to be.¹ On a jacket, the shell and lining are often made of different fibers, and a sweater may have ribbing with a little added elastane.

---

Certification Labels

Certifications are not part of the required fiber content label. When a product is certified, the certification usually appears on a hangtag or in the product description, and it says something different from the fiber content: how the fiber was grown or sourced, how the product was made, or how it was tested. Organic certifications such as the Organic Content Standard (OCS) and the Global Organic Textile Standard (GOTS) are explained in How Cotton Becomes Clothing, the Global Recycled Standard (GRS) for recycled fibers in Synthetic Fibers Explained, and OEKO-TEX Standard 100, which tests finished products, in What Are Rayon, Viscose, Modal, and Lyocell.

---

Where to Find It Online

When you shop online, the fiber content is usually in the product description, sometimes under “Details,” “Materials,” or “Fabric & Care,” and it is not always easy to find. FiberScore lists every product’s fiber content on the product card, so you can compare items side by side and filter by any fiber and percentage. Start with the Fiber Guide, or browse every fiber.

---

References

1. Federal Trade Commission. (2014, updated 2025). Threading Your Way Through the Labeling Requirements Under the Textile and Wool Acts. https://www.ftc.gov/business-guidance/resources/threading-your-way-through-labeling-requirements-under-textile-wool-acts

2. Federal Trade Commission. (2014). Clothes Captioning: Complying with the Care Labeling Rule. https://www.ftc.gov/business-guidance/resources/clothes-captioning-complying-care-labeling-rule