A garment's fiber content label looks like a simple ingredient list, but it is governed by a specific federal law, the Textile Fiber Products Identification Act, enforced by the FTC, with rules most shoppers have never read. The law requires fiber content to be listed by percentage of total weight, using standardized generic fiber names, in descending order. What it does not require is disclosure of every fiber present in every case, and the exception written into the rule changes what a percentage on a tag actually tells you.
- General rule
- Fiber content must be listed by percentage of total fiber weight, using generic fiber names (cotton, polyester, nylon), in descending order from highest to lowest percentage.
- The 5% naming threshold
- A fiber making up less than 5% of total weight can generally be labeled generically as "other fiber" instead of named specifically.
- Functional-purpose exception
- If a fiber under 5% serves a specific stated function, such as spandex added for stretch, it must be named and its percentage disclosed even below the 5% threshold.
- Wool exception
- Any amount of wool present must be disclosed by name and percentage, regardless of quantity; wool has no 5% minimum for naming.
- Manufacturing tolerance
- A small variance between the labeled percentage and the actual fiber content is permitted, to account for unavoidable manufacturing variation.
FTC, Threading Your Way Through the Labeling Requirements Under the Textile and Wool Acts; 16 CFR Part 303.
The functional-purpose exception is the most useful part of the rule for a shopper to know, because it explains why a tag might read "96% cotton, 4% elastane" instead of grouping that 4 percent into "other fiber." A fiber under 5 percent only qualifies for the generic "other fiber" label if it is not serving a named function the manufacturer wants to disclose. Elastane at 4 percent is almost always named specifically because its function, adding stretch, is the entire reason it was added and is relevant to how the garment performs. A synthetic filler fiber at the same 4 percent, added for a less marketable reason, is more likely to disappear into "other fiber" on the label, still fully legal.
This means the absence of a named fiber under 5 percent is not evidence of anything sinister. It is the label following the rule as written. What it does mean is that a label reading "100% cotton" and a label reading "96% cotton, 4% other fiber" could both be accurate for garments with a similar small amount of a non-functional secondary fiber, one just chose to disclose it and the other used the generic grouping the law permits.
Reading a fiber content label
- 01Read the order, not just the top line
Percentages are listed in descending order by weight, so the full list tells you the relative composition, not just the dominant fiber.
- 02Notice when a small percentage is named
A named fiber under 5% (like elastane) is usually there for a specific functional reason worth knowing about.
- 03Don't read "other fiber" as a red flag
It is a legal, standard label for fibers under 5% without a stated function, not a disclosure failure.
- 04Check wool content specifically if relevant to you
Wool must be disclosed at any percentage, so its presence (or confirmed absence) on the label is reliable.
The short version
- 01
Fiber content labels are legally required to list percentages by weight in descending order, using standardized generic fiber names.
- 02
Fibers under 5% can be generically labeled "other fiber" unless they serve a stated function (like added stretch), in which case they must be named.
- 03
Wool is exempt from the 5% threshold and must always be disclosed by name and percentage, however small the amount.
Questions
- 01Is the fiber content label the same as the care label?
No. Fiber content (what the garment is made of) is governed by the Textile Fiber Products Identification Act; care instructions (how to wash and dry it) are governed by a separate rule, the FTC's Care Labeling Rule. They often appear on the same tag but are legally distinct requirements.
- 02Can country-of-origin claims on the same tag be trusted the same way?
Country of origin is also a federally required disclosure on most textile products, covered by the same general labeling framework, though the specific rules for what qualifies a product as "Made in USA" versus requiring a foreign-origin disclosure involve additional FTC guidance beyond fiber content alone.
