Thread Count and Towel GSM: How Each Is Tested and Labelled

Thread count is ends plus picks per inch

ASTM D3775 measures end (warp) count and pick (filling) count on any woven fabric and reports each per inch or per centimetre. Thread count is the sum of the two per inch. ASTM terminology counts "multiple ply yarns" as "a single unit" (IDFL, ASTM definitions), so a two-ply yarn is one thread, not two.

ISO 7211-2:2024 counts threads per centimetre by three methods: A, dissecting the fabric; B, a counting glass, for fabrics above 50 threads per centimetre; and C, a traversing thread counter. In a dispute, method A takes precedence. To compare an ISO result with a US thread count, multiply each per-centimetre count by 2.54 and add them.

The same fabric gives very different numbers depending on how plies are treated:

The counts above are a worked example. In metric terms, 140 ends per inch is 55.1 ends per centimetre and 160 picks per inch is 63.0 picks per centimetre.

What US regulators have said about plied yarns

On 2 Aug 2005, FTC staff answered the National Textile Association on how to disclose thread count (FTC). The letter, signed by James A. Kohm, Associate Director of the Division of Enforcement, said consumers could be deceived by an inflated thread count reached by multiplying the actual count by the number of plies. Its example of a non-deceptive label was "300 thread count, two-ply yarn". A "600 thread count" claim for the same product would likely mislead consumers (Home Textiles Today, 12 Sep 2005).

The letter is a staff opinion, not a Commission rule. The law behind it is the FTC Act's ban on deceptive practices, which applies to any thread count printed on a US label or listing.

The US International Trade Commission went further. In investigation 337-TA-976, AAVN, Inc. of Texas named 15 respondents, mostly Indian mills and US importers. One exhibit to its complaint showed sheets sold as "800 Thread Count" that measured 252.7 threads. On 20 Mar 2017 the Commission issued a general exclusion order barring woven textile products "falsely advertised through a misrepresentation of thread count" from any source (Federal Register, 24 Mar 2017).

The order was rescinded in Mar 2021 at the complainant's own request, after it disputed the testing protocol US Customs and Border Protection used on shipments (Federal Register, 10 Mar 2021). The lesson for a mill holds either way: when a thread count is challenged, the only defence is a report to the method the buyer named.

Why this matters for Pakistani mills

In FY2024-25 Pakistan exported US$3,112.8 million of bed wear, up 11.07%, and US$1,082.6 million of towels, up 2.61%. Together that is 23.5% of US$17,887.0 million in textile exports (Towel Manufacturers' Association of Pakistan, from Pakistan Bureau of Statistics data).

Towel GSM is mass per unit area

GSM is grams per square metre. ASTM D3776/D3776M gives four options: A, a full piece, roll, bolt or cut; B, a full-width sample; C, a small swatch; and D, narrow fabrics. Option A is the one commonly used for commercial shipment acceptance. Unless the order says otherwise, results include selvages and are on conditioned fabric.

EN 12127 weighs small specimens cut from the fabric, and ISO 3801 covers woven fabrics. A swatch from the pile area and a weighing of the whole towel can give different figures, because hems and borders are woven differently from the pile. The specification has to say which one counts.

A worked example for the whole-towel route:

• Bath towel, 70 × 140 cm, so its area is 0.98 m²

• Conditioned weight 490 g

• GSM = 490 ÷ 0.98 = 500 g/m²

• The same towel in trade weight terms: 490 g × 12 = 5,880 g a dozen, or about 13.0 lb a dozen

Cotton takes up moisture from the air, so a towel weighed straight off a humid warehouse floor is heavier than the same towel after conditioning. Weigh after conditioning, and write that into the method.

Absorbency and the other tests buyers add

AATCC TM79 covers the water absorbency of yarns, fabrics and garments of any fibre content or construction. It is a drop test: a drop of water is placed on the fabric and the time until it is fully absorbed is reported in seconds. The order should say whether the towel is tested as received or after a stated number of washes.

ASTM D5433-24 is the US performance specification for towel products, from washcloths to bath sheets, for household and institutional use. It is voluntary: it applies by agreement between purchaser and supplier, with separate tables for terry and non-terry products, and without that agreement its tables serve only as a guide.

Every method below is on the Tti Labs ISO/IEC 17025 scope (PNAC LAB-022):

Colour fastness to washing and rubbing is usually on the same order; the textiles testing page lists those methods.

The clause to write into the order

A number without a method cannot be enforced. These lines can be tested:

• Sheets: "Thread count 300, determined by ASTM D3775, each plied yarn counted as one thread. Label: '300 thread count' for single-ply yarns, or '300 thread count, 2-ply yarn' where plied."

• Towels: "Minimum 500 g/m², whole towel, ASTM D3776 Option A, on conditioned fabric."

• Absorbency: "AATCC TM79, tested after the number of home launderings stated in the order."

• Tolerance: any tolerance on the count or the weight, written as a number. Without one, a count of 296 against a claim of 300 is open to argument.

Checklist before the goods ship

• Count ends and picks on production fabric, not only on the approved sample

• Check the yarn ply against the label wording

• Weigh towels after conditioning, by the option the order names

• Match the label, the hangtag and any online listing to the lab report

• Keep the report with the shipment documents, in case the count is challenged at the port or by the buyer

• Have the label and packing checked at pre-shipment inspection

Tti Labs tests thread count, GSM and absorbency in Lahore

Tti Testing Laboratories holds ISO/IEC 17025 accreditation under PNAC LAB-022, valid until 8 Aug 2027, for every method in the table above. Each test and its charge are confirmed in writing, with the turnaround, before any work starts (Tti Labs testing). The lab testing guide covers how to plan a test programme, and the certificates guide covers OEKO-TEX and other product certificates.

Book a thread count or GSM test with Tti Labs