The most common thread for a sewing machine is all-purpose polyester, typically sold as 40-weight or 50-weight on a standard spool. It works on cotton, linen, knits, denim, and most other fabrics you’ll encounter in home sewing. But “all-purpose” doesn’t mean it’s always the best choice. The right thread depends on your fabric, your project, and sometimes the specific stitch you’re using.
All-Purpose Polyester: The Default Choice
If you’re buying one thread to keep on hand, make it 100% polyester all-purpose thread. It has a slight give that prevents seams from snapping under stress, and it resists shrinking, fading, and moisture. It sews smoothly through cotton, linen, jersey knits, double knits, and denim without any special machine adjustments.
All-purpose thread is 3-ply, meaning three strands are twisted together for strength. This matters because some other threads (like serger cone thread) are only 2-ply and won’t give you as strong a seam in a standard sewing machine. If you see large, inexpensive cones of thread at the store, check whether they’re labeled for sergers. They’ll work in a regular machine, but the seams won’t hold up as well.
Thread Materials and When They Matter
Beyond polyester, threads come in cotton, silk, nylon, and various blends. Each has a specific strength.
Cotton thread is the traditional choice for quilting and works best on 100% cotton fabric. It produces less lint than polyester during high-speed stitching, and quilters prefer it because it bonds well with cotton batting and fabric. It doesn’t stretch, so avoid it for knits.
Core-spun thread combines the best of both worlds: a continuous polyester core wrapped in cotton or polyester yarn. You get polyester’s strength with cotton’s soft, matte finish. Many all-purpose threads are actually core-spun polyester rather than pure filament polyester.
Nylon thread has natural stretch and high tensile strength, making it the go-to for upholstery. It won’t snap every time someone sits on a reupholstered chair. Clear nylon monofilament thread (which looks like fishing line) is also nylon-based and useful for invisible hems or when you don’t want thread color to show.
Silk thread is fine, strong, and leaves almost no visible stitch impression. It’s ideal for tailoring, basting, and sewing silk or wool garments. The general rule for upholstery applies to garments too: matching your thread fiber to your fabric fiber gives the most natural results.
Understanding Thread Weight
Thread weight tells you how thick or thin a thread is, but the numbering system is counterintuitive. In the most common system (labeled “wt”), a higher number means thinner thread. A 50-weight thread is finer than a 30-weight thread. The logic: 50-weight means it takes 50 kilometers of that thread to weigh one kilogram, so more length per kilogram equals a thinner strand.
You may also see Tex or Denier numbers, which work in the opposite direction. Higher Tex and Denier numbers mean thicker thread. Here’s how the three systems roughly compare for the weight ranges you’ll actually use:
- Lightweight (50 to 100wt): Best for delicate fabrics like silk, chiffon, and voile. These fine threads prevent puckering on thin materials.
- Medium-weight (30 to 50wt): The all-purpose zone. This covers garment construction, quilt piecing, and everyday sewing on cotton and linen. A 40-weight thread is the sweet spot for most projects.
- Heavyweight (12 to 30wt): Built for upholstery, canvas, leather, and heavy denim. Also useful for bold decorative topstitching where you want the thread to be visible.
Matching Thread to Your Fabric
The simplest rule: lighter fabrics need finer thread, heavier fabrics need thicker thread. Using a heavy thread on chiffon will pucker the fabric and create visible stitch holes. Using a fine thread on canvas won’t provide enough seam strength.
For most cotton garments, a 40-weight all-purpose polyester is the standard choice. If you’re sewing sheer curtains or a silk blouse, step up to a 50 or 60-weight thread. For hemming jeans or sewing through multiple layers of denim, a 30-weight or dedicated topstitching thread handles the job without breaking.
Specialty Threads
Elastic thread stretches anywhere from 15% to 300%, depending on the product. It’s essential for activewear, compression garments, swimwear, and stretchy accessories like headbands. Working with it requires some machine adjustments: lower your tension, use a zigzag or stretch stitch instead of a straight stitch, and pair it with a ballpoint or stretch needle to avoid punching holes in knit fabric. Thread breakage is the most common problem, usually caused by tension set too high.
Metallic thread adds shimmer to decorative stitching and embroidery but is notoriously finicky. It requires a metallic needle with an oversized eye and a specially shaped groove that prevents shredding. Sew slowly and reduce your top tension.
Embroidery thread comes in polyester, rayon, cotton, and silk. Rayon and silk work well on lightweight and medium-weight fabrics, but polyester embroidery thread is stronger, more colorfast, and better for heavier fabrics. Use a machine embroidery needle (sizes 70/10 through 90/14) with its larger eye to protect the thread during dense stitch patterns.
Use the Right Needle
Thread and needle are a package deal. The wrong needle will shred your thread, skip stitches, or damage your fabric, no matter how good the thread is.
- Standard universal needles (80/12): Pair with all-purpose thread for most woven fabrics.
- Stretch or ballpoint needles (75/11 to 90/14): Use with elastic or all-purpose thread on knit fabrics. The rounded tip slides between fibers instead of piercing them.
- Topstitch needles (80/12 to 100/16): Feature an extra-large eye for heavy topstitching thread or doubled all-purpose thread.
- Metallic needles (80/12): Designed with a larger eye and special groove to prevent metallic thread from fraying.
The general principle: heavier thread requires a larger needle so the thread passes through the eye without friction. If your thread keeps shredding or breaking, sizing up your needle is the first thing to try.
Thread Quality Makes a Difference
Cheap thread causes more problems than it’s worth. Thread is made by twisting fiber staples together, similar to how yarn is spun. High-quality thread uses long staples, which creates a smoother, stronger strand with fewer loose ends. Budget thread uses short staples that shed more lint, break more easily, and leave fuzzy buildup inside your machine’s tension discs and bobbin case. That lint accumulation gradually degrades stitch quality and can lead to mechanical issues over time.
Reputable brands like Gutermann, Coats & Clark, Aurifil, and Mettler cost a bit more per spool but sew more consistently and produce cleaner stitches. If you’ve been fighting with thread breakage or messy tension on a well-maintained machine, the thread itself is often the culprit.
Spool Winding and Your Machine
Thread spools come wound in two ways, and placing them incorrectly on your machine can cause uneven tension or tangling. Cross-wound spools have thread wrapped in an angled, crisscross pattern. They need to sit on a horizontal spool pin so the thread pulls off the top of the spool. Stack-wound spools have thread wrapped in neat, flat layers. They belong on a vertical spool pin so the thread draws off the side.
Most home sewing machines have both a horizontal and vertical pin (or an adapter). If your thread keeps catching or looping on one pin position, try switching to the other before adjusting your tension settings.