Sewing Thread Label Specifications: Tex, Thread Count, Strength,… and Needle Size Explained
Sewing thread may account for only a small portion of a garment’s total material cost, but it plays a major role in seam strength, appearance, production efficiency, and long-term garment performance. For garment manufacturers, merchandisers, technical designers, quality teams, and apparel buyers, understanding sewing thread specifications is therefore essential. Terms such as Tex 27, Tex 40, 40/2, 60/3, ply, tensile strength, elongation, and needle size describe different characteristics of sewing thread. If these values are misunderstood, a factory may choose a thread that is too fine, too coarse, too weak, or incompatible with the sewing needle and fabric.
Common Thread Specifications Table – Below is a summary of how Tex, Ne construction, and needle sizes correlate to ensure seam quality:
| Tex | Ne (Construction) | Tensile Strength (cN) | Elongation (%) | Singer Needle Size |
|---|---|---|---|---|
| 18 | 60/2 | 555 | 19 | 9-10 |
| 27 | 40/2 | 850 | 20 | 11-12 |
| 40 | 40/3 | 1355 | 20 | 13-14 |
| 60 | 20/2 | 1889 | 21 | 14-16 |
| 80 | 20/3 | 2875 | 21 | 16-18 |
| 180 | 20/6 | 5975 | 22 | 22-23 |
This guide explains the most important sewing thread specifications used in the garment industry, including how to read thread numbers, how Tex works, what ply means, how thread strength is measured, and how to match thread size with the correct sewing-machine needle.
Basic Construction of Sewing Thread
Before reading specifications, it is important to distinguish between fiber, filament, singles yarn, ply, and finished sewing thread. Many spun sewing threads are made by first producing individual single yarns. Two or more of these singles can then be twisted together to create the finished thread. This process is known as plying. For example:
- 2-ply thread = two single yarns twisted together
- 3-ply thread = three single yarns twisted together
- 6-ply construction = six components, depending on the specific thread system and product construction
The number of plies influences the finished thread’s diameter, strength, appearance, and sewing performance. It is important not to automatically call these plies “filaments.” A spun sewing thread is built from spun yarns, while continuous-filament thread uses long continuous synthetic filaments. These are different thread constructions.
Structure of twisted sewing threads – Sewing thread is made up of multiple single filaments twisted together. The number of filaments directly determines the strength and robustness of the thread. For example, a “40/2” thread means that two filaments (of a fineness rating of 40) are twisted together. This is a common standard in general garment manufacturing.
How to Read a Label of Sewing Thread
If you see a label: “Tex 40 – 40/3 – 1355 cN – 20% – 3,000 m – Needle 12–13”, – here is the interpretation:
- Tex 40: Medium thickness for jackets or trousers.
- 40/3: Three filaments twisted for extra durability.
- 1355 cN: Strong enough for high-stress seams.
- 20%: Good flexibility for movement.
- Needle 12-13: The correct size to ensure smooth sewing without skipped stitches.
1. Tex – Thread Thickness
Tex is one of the most useful systems for describing thread size because it measures linear density directly. The basic definition is: Tex = grams per 1,000 meters of thread. For example:
- Tex 20 means 1,000 meters weighs approximately 20 grams.
- Tex 40 means 1,000 meters weighs approximately 40 grams.
- Tex 80 means 1,000 meters weighs approximately 80 grams.
Because Tex is a direct system, the rule is easy to remember: Higher Tex = heavier and generally thicker thread.
“Tex” measures the weight in grams of 1,000 meters of thread – Tex system visual thickness comparison. Lower Tex (18, 21, 27): Finer thread for precision items like lingerie or lightweight apparel. Higher Tex (70, 80, 150+): Thicker thread for heavy-duty products like jackets, bags, or leather goods.
Tex 20 vs. Tex 40 vs. Tex 80
Consider three thread sizes:
- Tex 20: relatively fine
- Tex 40: medium
- Tex 80: considerably heavier
| Tex Range | General Thread Size | Typical Application |
|---|---|---|
| Tex 15–24 | Fine | Blouses, lightweight shirts, linings |
| Tex 25–40 | Light–medium | T-shirts, shirts, dresses, general apparel |
| Tex 40–60 | Medium | Trousers, uniforms, jackets |
| Tex 60–90 | Heavy | Denim, workwear, heavy topstitching |
| Tex 100+ | Very heavy | Bags, footwear, technical products |
As Tex increases, the thread usually becomes more visible and capable of carrying greater loads, although actual strength depends on thread construction and fiber type. This means Tex 80 is not simply a “stronger version” of Tex 40. It is also physically heavier and may require a larger sewing needle and different machine settings.
Tex and Thread Count Work in Opposite Directions
| Thread System | Type of Numbering | Higher Number Means |
|---|---|---|
| Tex | Direct | Heavier / generally thicker thread |
| Cotton Count (Ne) | Indirect | Finer yarn |
This opposite relationship is one of the most common causes of confusion in sewing thread specifications. Remember: Higher Tex = coarser. Higher Ne = finer.
2. Ne (Construction) – Yarn Count and Number of Plies
A specification such as: 40/2, 60/3, 20/3 contains two pieces of information. Like “40/2” tells you:
- First number (40): The fineness of each single filament (higher = finer).
- Second number (2): How many filaments are twisted together. “2” mean two single yarns twisted together
There for: 40/2 = two 40-count yarns plied together. => Note: A 60/3 thread can be stronger than a 40/2 because it uses three plies, even though the individual fibers are thinner. Similarly:
- 60/2 = two 60-count singles
- 60/3 = three 60-count singles
- 40/3 = three 40-count singles
- 20/2 = two 20-count singles
- 20/3 = three 20-count singles
3. Tensile Strength (cN) – How Much Force the Thread Can Withstand
Tensile strength, often shown as breaking strength, tells you how much pulling force the thread can withstand before it breaks. It is commonly expressed in cN, or centiNewtons. For reference: 100 cN = 1 Newton So if a thread has a breaking strength of: 1,300 cN that means it breaks at approximately: 13 N of tensile force under the specified test conditions.
4. Elongation (%) – How Far the Thread Can Stretch Before Breaking
Elongation at break measures how much a thread can extend before it finally breaks. It is expressed as a percentage. Suppose a thread has Elongation: 20% Conceptually, if a test length were 100 mm, the thread could extend to roughly 120 mm before breaking under that test setup. So:
- Lower elongation = thread stretches less.
- Higher elongation = thread stretches farther before failure.
Conclusion / Final Words
Sewing thread specifications may seem technical, but they directly affect how well a garment is sewn and how long its seams perform. Tex and Ne help identify thread size, ply describes construction, while tensile strength and elongation indicate how the thread behaves under stress. By matching these specifications with the fabric, stitch type, needle, and final garment use, manufacturers can reduce sewing problems and achieve cleaner, stronger, and more consistent seams.
40/2 = two 40-count single yarns plied together. 20/2 = two 20-count single yarns plied together. 20/3 = three 20-count single yarns plied together.
FAQs About Sewing Thread Specifications
In Short, What do the numerical values in thread construction, such as “40/2” or “60/3”, actually represent?
These numbers refer to the thread’s physical structure and composition. The first number (e.g., 40 or 60) indicates the fineness of the single filament; a higher number generally implies a finer, thinner filament. The second number (after the slash, e.g., 2 or 3) represents the number of these single filaments twisted together to form the final thread. Therefore, a “40/2” thread consists of two filaments with a fineness rating of 40 twisted together. A “60/3” thread comprises three filaments of fineness 60. This construction directly influences the thread’s thickness and durability, with a higher number of twisted filaments typically resulting in greater tensile strength.
In short, How is the “Tex” system used to measure thread thickness?
The “Tex” system is a standard unit of measure used to determine the weight and thickness of a thread. Specifically, it indicates how many grams 1,000 metres of that thread weigh. For instance, if a thread is labeled as “27 Tex,” it means that 1,000 metres of that specific thread weighs exactly 27 grams. Because this is a direct numbering system, the relationship is straightforward: the higher the Tex value, the heavier and thicker the thread is. Manufacturers use this value to categorize threads, ranging from fine threads (Tex 18 or 21) to much thicker options (Tex 60 or 80). => Read More: How the “Tex” System Measures Thread Thickness ?
Why is Tensile Strength (cN) a vital metric for product quality?
Tensile strength measures the maximum force a thread can withstand before it snaps, expressed in centiNewtons (cN). This metric is imperative for ensuring the longevity and durability of the final garment. A higher cN figure indicates a stronger thread capable of enduring significant stress. For example, a fine thread (Tex 18) might have a tensile strength of around 555 cN, whereas a heavy-duty thread (Tex 60) can withstand up to 2,085 cN. selecting a thread with adequate tensile strength prevents seam failure during the garment’s use.
How does “Elongation at Break” affect the suitability of thread for different garments?
Elongation at break is measured as a percentage and indicates how much a thread can stretch relative to its original length before breaking. This characteristic is particularly significant when manufacturing flexible items such as sportswear, underwear, or activewear. If a garment is designed to stretch with the wearer’s movement, the sewing thread must possess high elongation properties to expand along with the fabric. If the thread lacks sufficient elongation, the seams are likely to snap when the fabric is stretched, compromising the garment’s integrity.
How do I determine the correct Singer Needle Size for a specific thread specification?
The Singer needle size must be compatible with the thickness of the thread to ensure smooth production and high-quality seams. Using the wrong needle size can lead to thread breakage or skipped stitches. Generally, finer threads (like Tex 18-24) require smaller needles, such as sizes 9-11, to maintain precision. Conversely, thicker, heavy-duty threads (like Tex 60-80) require larger needles, typically sizes 16-18, to accommodate the thread’s diameter without friction. Matching the needle size to the thread specification ensures the production process remains efficient and the seam finish is clean.
Can you provide examples of thread specifications used for heavy-duty versus light-duty applications?
For heavy-duty applications like jeans, workwear, or jackets, manufacturers typically use threads with specifications such as Tex 60 or Tex 80. These might appear as “20/2” or “20/3” in construction, offering high tensile strength (e.g., 2,085 cN or higher) to withstand rough usage. In contrast, for light-duty applications like shirts, blouses, or lightweight fashion items, finer threads are selected. These generally fall in the Tex 18 to Tex 24 range, with constructions like “60/2” or “50/2,” and lower tensile strengths (around 555 cN to 800 cN) to ensure the seams are unobtrusive and delicate.
Aside from technical specifications, what other factors should be considered when selecting thread?
While specs like Tex and tensile strength are foundational, you must also consider the compatibility of the thread with the fabric material. The weight of the thread should align with the weight of the fabric; heavy fabrics require stronger threads, while delicate fabrics need finer threads to avoid puckering. Additionally, properties such as color fastness are imperative to ensure the thread does not fade or bleed during washing. Shrinkage is another factor; the thread should have a shrinkage rate similar to the fabric to prevent the seams from distorting after the garment is laundered.
