Choosing the wrong thread causes many of the same problems as choosing the wrong needle — broken thread, weak seams, puckering, or a seam that shows in a color meant to blend in. Thread selection actually has two separate parts: the fiber type (what the thread is made of) and the thread size (how thick it is). This guide covers both, and pairs directly with the sewing machine needle sizes guide, since needle and thread are always chosen together.
Thread Fiber Types
| Thread Type | Made From | Best For |
|---|---|---|
| All-purpose polyester (spun) | Spun polyester staple fiber | General garment construction; the industry-standard default for strength and colorfastness |
| Filament polyester | Continuous polyester filament (often trilobal for sheen) | Decorative and topstitching work needing a silk-like shine with better durability than rayon |
| Core-spun polyester (cotton-wrapped) | Polyester filament core wrapped in cotton fiber | High-speed industrial sewing — combines the polyester core's strength with the cotton wrap's needle-heat resistance and smooth sewability |
| Cotton | 100% cotton staple fiber | Natural-fiber garments, quilting, heirloom sewing, decorative stitching; has little stretch, so it is a poor match for knits |
| Nylon (monofilament) | Single continuous nylon strand | Blind hems and "invisible" stitching |
| Nylon (texturized/upholstery) | Textured or heavy nylon filament | Serger rolled hems (texturized); heavy-duty, rot-resistant outdoor and upholstery seams |
| Silk | Natural continuous silk fiber | Hand-sewing, tailoring, basting, and fine or delicate fabrics |
| Machine embroidery thread | Fine polyester, rayon, or cotton | Decorative embroidery where color range matters more than seam strength |
Understanding Thread Size: Why the Numbers Look Confusing
Thread size is not measured on one universal scale — several numbering systems are used across different regions and product categories, and some run in opposite directions from each other. Knowing which system you're looking at is the key to reading a spool label correctly.
Tex System
Tex is a direct system: it is the weight in grams of 1,000 meters of thread. Because it directly measures weight per length, a lower Tex number means a finer thread; a higher Tex number means a thicker thread. Tex is widely used internationally and is the most straightforward system to compare across brands.
Denier System
Denier works the same direction as Tex (lower = finer, higher = thicker) but measures grams per 9,000 meters. It is most often used for continuous-filament threads such as nylon and polyester.
English Cotton Count (Ne)
Cotton count is an indirect system — it counts how many 840-yard hanks make up one pound of thread. Because more hanks per pound means a finer thread, a higher Ne number means a finer thread — the opposite direction from Tex. This is the traditional system for cotton and many spun threads, and the same logic underlies yarn count in spinning.
Thread "Weight" (wt)
This is the number printed on most consumer embroidery and quilting thread spools (e.g. 40wt, 50wt, 60wt). It is also an indirect system: a higher weight number means a finer thread. 40wt and 50wt are the most common general-purpose and machine-embroidery sizes; 60wt and finer suit detailed micro-quilting and bobbin work; 12wt and heavier are bold, visible decorative threads.
Ticket Number (Tkt) — the one to double-check
"Ticket number" is a manufacturer's commercial reference size, and unlike Tex or Denier, it is not applied consistently across the industry — this is the single most common source of thread-size confusion. Many industrial and bonded threads (used for leather, upholstery, and technical sewing) use a ticket number that approximates the Tex value directly, so a higher number means a thicker thread — for example, Tkt 69 (≈ Tex 70), Tkt 92 (≈ Tex 90), and Tkt 138 (≈ Tex 135) get progressively heavier. But ticket numbers derived from cotton-count conventions run the opposite way, like Ne, where a higher number means a finer thread. When comparing thread across brands or systems, check the Tex or Denier value on the label rather than relying on ticket number alone.
Matching Thread Size to Fabric and Needle
As a general rule, thread and needle size scale together: fine thread pairs with a smaller needle on lightweight fabric, and heavier thread needs a larger needle — partly because the needle's eye has to accommodate the thread without excessive friction, which is also why a heavy topstitching thread needs a topstitch needle's larger eye, not a standard one. Lightweight fabric (chiffon, fine cotton) generally takes a fine, lower-Tex or higher-wt thread with a 60/8–70/10 needle; medium-weight fabric (quilting cotton, shirting) takes an all-purpose 40wt/Tex 30-ish thread with an 80/12 needle; and heavy fabric (denim, canvas) takes a heavier core-spun or upholstery thread with a 90/14–100/16 needle.
How to Choose the Right Thread
Start from the fiber, not the number: match polyester (all-purpose or core-spun) to most garment construction, cotton to natural-fiber quilting and heirloom work, nylon monofilament to invisible hems, and upholstery-grade nylon or heavy core-spun polyester to outdoor or high-abrasion seams. Once the fiber type is settled, choose the thickest thread the fabric and needle can accommodate without adding bulk to the seam — going heavier than needed causes visible, stiff seams; going too fine for the fabric produces weak seams that fail under stress.
Frequently Asked Questions
What is core-spun thread, and why does the garment industry use it?
Core-spun thread has a polyester filament core wrapped in cotton fiber. The polyester core gives it strength; the cotton wrap gives it smooth sewability and resistance to the heat a needle generates at high industrial sewing speeds, which is why it's a standard choice in garment factories.
Why does a higher ticket number sometimes mean a thicker thread and sometimes a finer one?
Because "ticket number" isn't one standardized system — some manufacturers base it on Tex (higher number = thicker), others base it on cotton count (higher number = finer). Always check the Tex or Denier figure on the label when it's available, especially when comparing threads from different brands.
What thread works best on an overlock/serger machine?
Sergers typically use lighter, all-purpose polyester or texturized nylon thread, since they use multiple threads (2–5) at once and a lighter thread keeps the seam flexible. See overlock machine (serger): definition, parts, benefits & uses for how the stitch itself is formed.
Can cotton thread be used for all garment sewing?
Not ideally. Cotton thread has little stretch, so it performs poorly on knit or stretch fabric, where the seam needs to stretch with the fabric. Polyester is the more common general-purpose choice for exactly this reason.