For 50 wt thread, the most common and recommended sewing machine needle size is 80/12, though you can often use a slightly smaller 70/10 for finer fabrics or a slightly larger 90/14 for thicker materials like denim or quilting, especially if you encounter shredding or skipped stitches; always test on a scrap first.
When using a 40 weight thread, use a size 80/12 needle. If using a thread finer than a 40 weight, such as a 50 weight, use a smaller needle size such as 70/10. Micro threads use needle size 65/9 or 60/8.
Medium Weight Threads
These are the types of threads that you will most frequently find, most often 40 or 50wt. They can be used for most construction, quilting, machine embroidery, sergers, and general purpose sewing.
60 threads should be used when a design calls for small lettering or fine detail. Always use a #65 needle and increase density when sewing with 60 weight thread.
Each yarn will have a recommended knitting needle size to be used with it, depending on the yarn weight. The thicker the yarn, the larger the needle size you will need to use with it. For example most DK yarns recommend 4mm needles, whereas chunky yarns use size 6-7mm.
70/10 – 100 weight threads. 80/12 – 50 weight threads. 90/14 – 40 weight threads. 100/16 – 30 weight threads and thicker.
Tex is an accurate measurement and is considered a direct numbering system, meaning the higher the Tex number, the heavier the thread. On the other hand, the weight system, most popular in the U.S., is not a direct numbering system because the larger the number (30 wt., 40 wt., 50. wt., 60 wt.), the finer the thread.
Gutermann Cotton Sewing Thread is a fine 50 weight cotton thread but strong with a silky finish for users who prefer to sew with cotton. Suitable for hand or machine sewing, Gutermann Cotton Thread is a 100% longstaple mercerized cotton sewing thread.
50 wt thread is a fine, versatile thread ideal for piecing, general sewing, and light quilting. It creates flat seams, blends well with fabric, and works beautifully in both domestic and longarm machines.
40wt is a thread that is significantly heavier than 60wt, and noticeably heavier than the 50wt. While it is always good to have different size threads on hand, just in case, I don't usually sew on heavy fabrics, but I do consider the 40wt thread essential for my sewing stash.
Choosing the right needle size for sewing is all about three things: fabric, thread, and technique. Use both metric and US sizes to find the perfect match quickly. For fine fabrics, sizes 60/8–70/10 are best. For light to medium fabrics and many garments, sizes 75/11–80/12 are ideal.
The tip of the Jersey Needle (SUK) is rounded so that it can push the fibers of the fabric to the side, penetrating the gaps in between. The needle therefore prevents the loop from getting damaged. If the knitted fabric contains spandex (i.e. it is elastic), use a Stretch Needle.
Cotton fabric works best with a sewing machine tension setting between 4 and 5. This range ensures smooth, even stitches without damaging the fabric.
For the recommended heavy-duty threads (Tex 70 through Tex 135), appropriate needle sizes range from 100/16 up to 125/20 or occasionally 130/21.
Sarah wrote: If you've been stitching too long the needle can become too hot and it can shred the thread. Change the needle!
The higher the number, the finer the thread. So 30 wt. is actually heavier and thicker than 50 wt., and 100 wt. is incredibly fine. Think of it like a seesaw. The heavier (thicker) the thread, the lower the number, and the heavier end tips down.
Needles sizes #65/9 to #75/11 are your most popular size needles and work well with 60 and 40 weight threads.
What size needles should I use for chunky wool? A pattern using chunky wool will generally need large needles. Around 7 - 8 mm is average, while 5.5 - 6 mm will give you a tighter fabric. Super chunky wool, which is ideal for making a very thick blanket, will need even bigger needles.
DK yarns are lighter than worsted, but heavier than sport. DK yarn is equivalent to #3 Light on the Standard Yarn Weight System. It is often used for infant wear and lightweight garments.
For both sizing systems, the lower the number the finer the needle and the higher the number the larger the needle. Most needle companies show both sizes on the package. A good rule of thumb to keep in mind: the lighter the fabric the smaller the needle size and the heavier the fabric the larger the needle size.