Thickness of sewing threads by number: full guide and tables of correspondence

Anyone who has ever picked up a needle and tried to fix a sprawling seam on their favorite shirt or sew curtains, faced with incomprehensible numbers on the coil. Why are some strings written “40”, others “60”, and others even “No. 10”, and how to know what exactly is suitable for your sewing machine? An error in choice can lead to a break in the thread, break the needle or, worse, damage to expensive fabric that will be impossible to restore.

There are several numbering systems in the world of textiles, and they often contradict each other, creating confusion among beginners and even experienced craftsmen. Thickness of the thread This is not just an abstract concept, but an exact physical parameter, on which the strength of the seam and the appearance of the product depend. In this article, we will analyze the basic metric systems, learn how to translate one value into another and select the perfect pair of “needle threads” for your tasks.

Understanding the labeling will not only save you time on the cross-stitching, but also professionally approach the choice of materials for any project, whether it is the finest silk or tight jeans. Let’s find out what is behind these mysterious numbers.

Basics of the metric numbering system

The most common system in the post-Soviet space and Europe is metric numbering, designated as Nm. The principle here seems paradoxical only at first glance: the higher the number of the thread, the thinner it is. This is logical, if you remember the definition: the number shows how many meters of thread is contained in one gram of weight.

If you see the markings, Nm 10This means that one gram of this material contains 10 meters of length. If you have a numbered coil in front of you. Nm 80In one gram will be 80 meters, which automatically makes the thread much thinner and lighter. Metric number It is a key parameter in the calculation of tissue density and equipment selection.

For household use, threads in the range from 10 to 80 rooms are most often found. Strings No. 10-20 are designed for very rough work, such as cutting carpets or tailoring tarpaulins. For home sewing, the optimal choice is 40, 50 and 60, which provide a balance between strength and aesthetics of the seam.

⚠️ Attention: Never use 10-20 threads in modern household sewing machines without first checking the instructions. Their thickness can lead to a stuck shuttle mechanism and deformation of the needle driver.

Tex System and Industrial Standards

Unlike the metric system, the international system Tex (Tex) works on the opposite principle, which often confuses those who are used to the metric. Here the number of the thread indicates the weight in grams of 1000 meters of its length. Therefore, the higher the number in the Tex system, the thicker and heavier the thread.

This system is an ISO standard and is widely used in industrial production, as well as on the labels of imported threads from the United States and Asia. For example, thread Tex 40 It will be much thicker than the thread. Tex 15. Understanding this distinction is critical when ordering materials for a professional atelier or factory where deviation in seam density is unacceptable.

There is also the concept of “decorative thread”, which can have a non-standard numbering. In such cases, manufacturers often specify both values or use special designations for multisyllabic threads. Linear density in tex allows you to accurately calculate the consumption of material for a large replication of products.

Translation formula

To translate the metric number (Nm) to Tex (Tex), use the formula: Tex = 1000/Nm. For example, for thread number 50 (Nm 50), the calculation would be: 1000 / 50 = 20 Tex.

American and English systems (Cotton Count)

The English system known as Cotton Count (Denoted Ne or cc), historically developed in the UK and the USA and is still actively used for cotton threads. The logic here is similar to the metric: the number indicates the number of passes (hanks) 840 yards long (about 762 meters) that weigh one pound.

As in the metric system, there is a rule: the higher the number, the thinner the thread. However, the ratios are not linear compared to the metric. For example, the popular cotton thread for quilting number 50 in the English system will have a completely different physical thickness than the metric 50. This is important to consider when working with vintage patterns or American equipment.

Often on the coils you can find double markings, for example, 50/3. The first digit (50) indicates the tonin of the individual fibers, and the second (3) indicates the number of threads twisted together. A tight thread It directly affects its strength and viscousness.

• 🧵 Single-stranded (1-ply): Used for overlocks and sewing machines, give a flat seam.
• 🧶 Two-stranded (2-ply): Standard for household sewing machines, provide good strength and elasticity.
• 🪡 Tri-stranded (3-ply): They are used for decorative lines and work with dense fabrics, give a three-dimensional relief seam.

Table of conformity of numbers and thicknesses

In order not to get confused in the variety of systems, it is most convenient to use summary tables. Below are the basic values that will help you quickly navigate when buying materials in the store or online. Keep this information, it will be useful when working with different types of tissues.

Appointment	Metrica (Nm)	Tex (Tex)	Angle. (Ne)	Recommended needle
Rough fabrics, tarp	10 - 20	100 - 50	7 - 14	130 - 160
Jeans, coat fabrics	30 - 40	33 - 25	20 - 30	90 - 100
Paid, costumed	50 - 60	20 - 16	40 - 50	75 - 80
Silk, chiffon, batiste	70 - 80+	14 - 12	60 - 80	60 - 65

This table is averaged, as manufacturers can make small adjustments to the production technology. Always pay attention to the recommendations indicated on the packaging of a particular brand of thread. Compatibility of materials - the guarantee of the durability of your product.

How to pick up a needle under the thickness of the thread

The right needle is 90% of sewing success. If the needle is too thin for the chosen thread, the latter will begin to tear, shag, or get stuck in the ear, causing stitches to pass. If the needle is too thick, it will leave large holes in the tissue and can damage its structure.

There is a simple rule: the needle’s eye should be about 30-40% wider than the thread so that the thread passes through the tissue freely, without friction. Friction heats the filament, which is especially critical for synthetic materials that can melt and turn into a lump. Needle diameter It must be consistent with the density of the tissue and the thickness of the thread seam.

For standard household tasks, such as sewing bedding or repairing clothes, needles No. 75 or No. 80 paired with threads No. 40-50 are ideal. To work with knitwear, be sure to use rounded-tipped needles (Jersey/Stretch), which push the loops of the fabric apart rather than piercing them, preventing puffing.

⚠️ Attention: If you hear a characteristic click when sewing or see that the thread fluffs heavily at the exit of the needle, stop immediately. This is a sure sign that the needle number is chosen incorrectly or it is blunted.

Materials threads and their impact on the number selection

The number is not the only thing to look at. The material from which the thread is made also dictates its own selection rules. Natural threads (cotton, flax, silk) and synthetic (polyester, nylon, viscose) behave differently even at the same thickness.

Polyester threads, such as popular LL (Lavsan-Len) or pure polyester, have high tensile strength and elasticity. They are often used in a mixture with cotton to give strength. Cotton threads are softer, they are ideal for natural fabrics, but wear out faster and can shrink when washed.

For elastic fabrics (stretch, knitwear), it is critically important to use filaments with the addition of lycra or special textured polyester filaments. The usual twisted thread No. 40 will simply burst when the fabric is stretched, and the seam will disperse. Stitch elasticity It must be consistent with the elasticity of the material.

Frequent errors in choosing thickness

One of the most common mistakes is using old stocks of threads that are stored for years. Over time, the thread loses strength, becomes brittle and changes its physical properties. Even if the number on the coil fits, the thread itself can break with minimal tension.

Also, the masters often ignore the direction of the winding. On some industrial machines and overlocks, it is important which side of the coil the thread is reeled from. Incorrect installation of the coil creates additional resistance, mimicking the effect of “too thick thread”, which leads to permanent breaks.

Don’t save on threads for visible lines. Cheap threads often have uneven thickness along the entire length, which leads to knots and breaks at the most inopportune moment. Quality of the crookIt's about the look of the product.

Can I use the No. 10 thread in a household machine?

Using threads No. 10 in a standard household car is highly recommended. They are designed for hand sewing very rough materials or stacking. The mechanism of the household machine is not designed for such a thickness that will lead to breaking the needle, knocking down the rhythm of the shuttle and possible damage to the engine.

What do two numbers mean by fraction, like 45/2?

A 45/2 record means that the thread consists of two threads twisted together, each with a metric number 45. The final thickness of such a thread will be smaller (that is, the thread will be thicker) than that of single thread No. 45. It's a composite number.

Why does the thread always break, even though the needle number is correct?

There may be several reasons: the thread has dried up and become brittle, the thread is not properly filled (it did not get into the compensation spring), too strong tension of the upper thread or there are burrs on the coil that cut the thread when coiled.

How to store threads so that they do not deteriorate?

The threads should be stored in closed boxes or boxes, away from direct sunlight and heat sources. Optimal humidity will prevent drying of natural fibers and the “aging” of synthetics. Do not keep them in the bathroom or on the balcony.

What is the difference between a sewing machine and an overlock?

Overlock threads (often labeled as Overlock) are usually thinner (No. 80 and higher in the metric) and have a special winding structure to unwind at tremendous speed without entanglement. The use of ordinary threads in the overlock can lead to breaks, and overhead in the machine - to too weak, "thin" seam.