Threads 101- Part 2

THREADS 101 – Part 2

Weight, ply and needles.

By Jenn Long



Thread weights are pretty confusing.  There are many different ways manufacturers determine the weights and measurements of threads.


Most thread in U.S. stores print the thread weight on the spool.  Some sources state that this system is actually a length system, i.e. how many meters equal one gram. However, all one needs to remember is the smaller the number the THICKER the thread.   Commonly used are 12wt, 30wt, 40wt, 50wt, and 60wt. This system is not entirely dependable because one brand will have 50wt which could actually be different from another brand.  We will go into greater details about these weights in the next section.


Denier relates to weight in grams of 9000m of thread. A larger number indicates a heavier thread.  This is usually applied to the fineness of silk, rayon, or nylon yarns.


Thread Tex relates to weight in grams of 1000m of thread. Larger Tex numbers are heavier threads.  This method is becoming more and more the new standard.   Wiki Article

 Note:  You may encounter thread that is only stamped with the number standard.  This number system was developed in Japan and is known as the Gunze Count system.  The number standard is used on many thinner threads and is written as No. 50 (or #50) or No. 100 (or #100). Many people confuse this with a weight measurement. The smaller the number, the heavier the thread.  That part is the same as by weight. But a spool of thread stamped with No. 100 does not mean it is a 100 weight thread. One spool of thread may be stamped No. 100, another spool may be stamped 100 wt., and yet another spool of thread may be stamped 100/2. All three of these are measured using different standards and don’t assume they are similar in size.
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When comparing threads, make sure you use a consistent standard of measurement.

Generally, 40 wt =240 denier=Tex 25.

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There is no reason to talk about thread without considering needles.  Generally, you match the type of needle to the fabric.  Jeans needles for denim, etc.  But the size of needle should correlate with your thread.

Schmetz, a leader in the sewing needle industry states that 40wt/240 denier/Tex 25 all work in a size 75/11 needle. Schmetz also advises that the diameter of the eye of the needle should be 40% larger than the diameter of the thread.  A bit confusing?  Yes.  So in plain-talk, consider a larger needle when using threads heavier than 40wt/240denier/tex25. Consider using a smaller needle when using finer threads.


Yep you have seen it but what in the world does it mean!? We are not talking about toilet paper, but thread ply.   When thread is made, the ply refers to how many strands are twisted around to make the thread.  A 3-ply will be stronger then a 2-ply.  You may see on a spool 50/2 or a 50/3.  This means it is 50wt thread but one is 2 ply and the other is 3.  This is why measuring by weight (although it is really length) is not accurate.  A 50/2 will be lighter thread then a 50/3.

Stay tuned for Threads 101 – Part 3

Read Threads 101 – Part 1 here!

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Sewing Threads by the Number


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