Introduction
You’ve probably stood in front of the thread rack, squinting at labels like “40 wt” or “50 wt” and wondered what it all means. Is a higher number better? Should you always grab the finest thread you can find? It’s a common question, and the answer isn’t as straightforward as you might think. In sewing, thread weight (often written as “wt” or “Ne”) describes the thickness – the higher the number, the finer the thread. So 60 wt is thinner than 30 wt. But “better” depends entirely on what you’re making. A heavy denim jacket needs a different thread than a delicate silk blouse. Let’s cut through the confusion and help you pick the right cotton thread for your project, without falling into the “higher is always better” trap. En savoir plus
Criteria de choix
- Thread weight vs. fabric weight. Match your thread to your fabric. For heavy fabrics like canvas or upholstery, use a thicker thread (30–40 wt). For lightweight fabrics such as lawn or voile, a finer thread (50–60 wt) works best. Using a thick thread on thin fabric can cause puckering, while a fine thread on heavy cloth may snap under stress.
- Ply count matters too. A 2-ply thread is made from two strands twisted together, 3-ply from three, and so on. Generally, more plies mean stronger thread, but they also increase thickness. A fine thread can still be strong if it’s high-quality mercerised cotton with multiple plies. Don’t just look at the weight number – check the ply.
- Project type dictates choice. Quilting usually calls for 40 or 50 wt cotton – it’s durable but not too thick. Garment sewing often uses 50 wt for seams and 60 wt for fine hems or buttonholes. Embroidery thread is typically 40 wt for a bold stitch, while 60 wt is used for delicate detailing. Always consider the stitch function: topstitching benefits from a slightly heavier thread so it stands out.
- Needle size compatibility. A fine thread (60 wt) needs a small needle (size 60/8 or 70/10) to avoid skipped stitches. Heavy thread (30 wt) requires a larger needle (80/12 to 90/14). Wrong needle size leads to tension problems, broken threads, or damage to the fabric. Check your machine’s manual for recommendations.
Avantages
Choosing the right cotton thread – not necessarily the highest number – brings several benefits. First, your stitches will lie flat and even, without that annoying wrinkling or “shirring” that happens when thread and fabric are mismatched. You’ll also reduce the risk of thread breakage mid-project; a fine thread on heavy fabric is prone to snapping, while a thick thread on delicate cloth can cut through the fibres. Proper thread selection also improves tension. When the thread weight matches the fabric, your sewing machine runs smoothly, and you waste less time fiddling with dials.
Another advantage is better appearance. Fine threads (like 60 wt) create nearly invisible seams – perfect for heirloom sewing or when you want the fabric to shine. Heavier threads (40 wt and below) give a noticeable, decorative stitch that adds structure and texture. For example, topstitching on a pair of jeans looks smart with a 30 wt thread. And because cotton is a natural fibre, it doesn’t slip or stretch like polyester, so your seams stay put after washing. Finally, using the correct thread weight extends the life of both your project and your machine. Less strain on the needle bar and hook means fewer repairs – a win for your pocket and your sanity.
FAQ
What do the numbers like 40wt and 50wt actually mean?
They refer to the thread’s thickness using the “cotton count” system. A 40 wt thread means that 40 kilometres of it weigh 1 kilogram. The higher the number, the finer the thread – so 60 wt is thinner than 30 wt. This system is standard for cotton threads but you might also see “Tex” or “Denier” for synthetics. Just remember: bigger number = thinner thread.
Is 60wt cotton thread stronger than 40wt?
Not necessarily. Strength depends more on the ply and the quality of the cotton than on the weight number alone. A high-quality 3-ply 60 wt thread can be very strong, but a cheap 2-ply 40 wt thread might break easily. For heavy-duty seams, go for a thicker thread with more plies. For lightweight fabrics where strength isn’t the priority, a fine thread is absolutely fine – but don’t expect it to hold up to strain.
Can I use embroidery thread for regular sewing?
Yes, but choose the weight wisely. Standard embroidery threads are 40 wt mercerised cotton – the same as many all-purpose sewing threads. So you can definitely use them for seams, hems, or topstitching. However, some embroidery threads are designed with a special finish for sheen and may be slightly more slippery. Test a sample first. If you need a finer thread for delicate work, go up to 50 or 60 wt embroidery thread.
Conclusion
So, is higher better? Not on its own. The best cotton thread is the one that matches your fabric, project, and technique. A higher number gives you a finer thread – brilliant for lightweight materials and invisible stitching, but not for heavy denim or upholstery. Instead of chasing the biggest number, think about what you’re making. Keep a range of 40 wt, 50 wt, and 60 wt in your stash, and you’ll be ready for almost anything. And remember to pair the right needle and tension with your thread choice. With a bit of practice, you’ll develop an instinct for it – and your stitching will thank you. Happy sewing!
