Those Pesky Numbers

Maurice Brassard Cotton Yarn

New weavers sometimes have a bit of a challenge coming to grips with the numbering systems used to identify their yarns.

In knitting, word descriptions are used, but in weaving, yarns are generally numbered, such as 2/8 or 5/2.  These numbers are referred to as the ‘count’.  Then it must be determined whether the numbers are the old ‘imperial’ way of numbering or one of the metric numbering systems (see chart at the end for details).

So, yes, it does get a bit confusing!

There can also be an assumption that any yarn with the same count number will be identical in terms of characteristics.  Unfortunately, that is not always the case.

The only thing the numbers refer to is how many yards per pound, meters per kilo, or 100 grams, etc.  The numbers are the ‘count’ but they don’t tell someone how the fibres have been prepared for, and then spun.

Does this make a difference?  Yes, it can!

I came to weaving via spinning and I learned just enough to understand how the spinning processes can affect how the yarn behaves, and why it is important to know as much as possible about how yarns are constructed.

The imperial count system can also be confusing because different fibres have a different base, or value, for a number 1 count.  For example, cotton has a base of 840 yards per pound for a number 1 count.  Meanwhile, worsted wool has a base of 560 yards per pound for a number 1 count.

Recently I purchased some of the Gist Array wool yarns from SweetGeorgia, in part because it’s a bit difficult to find finer-wool yarns, and I wanted to see how the Array behaved and how it wet finished to the final, finished state.  Part of getting to know a new-to-me yarn is going through all the information I can get my hands on, and I noticed that it was labelled as a ‘worsted’ yarn and that the count was given as 2/12.

With a base of 560 yards per pound, how many yards per pound can be worked out by a simple calculation:  560 x 12 = 6720 divided by 2 = 3360 yards per pound.

Cotton yarn with a base of 840 for a number 1 with a count of 2/8 (or 8/2) would work out to 840 x 8 = 6720 divided by 2 = 3360 yards per pound.

You might assume then, that whatever you have been using for epi for 2/8 cotton would be the same for the 2/12 worsted wool.    

Wool and cotton are quite different in their structure, their inherent fibre characteristics might well behave quite differently in the loom, but also in the wet finishing.  Always a good idea to weave a sample at the epi and in the weave structure you intend to use, and then wet finish it to determine if you have calculated correctly to get the quality of cloth you desire.

Now, about the order those numbers come in.  When looking at the number that tells how many yards per pound or meters per metric, generally the larger of the two numbers is the single and the smaller of the two numbers is how many of those singles have been twisted together.  So, a yarn described as 2/12 will have two #12 singles twisted together.  There can be more than two singles, however – there can be 3 or 4, or even 8.  And some yarns can be ‘cabled’ (i.e. several 2 ply yarns all twisted together).

One of the yarns that many weavers use is cotton.  It can come in a variety of presentations.  In Canada, unmercerized cotton is quite common, while in the US, mercerized cotton is favoured.  It wasn’t until I started traveling to the US and saw the US quality of 8/2 cotton that I began to understand why many didn’t like it and preferred the more expensive mercerized cottons.  The two yarns come in slightly different sizes and the US yarns are generally labelled with the count first and then the ply (i.e. 10/2, 5/2).  The unmercerized cotton yarn comes in 2/16, 2/8, and some cabled yarns of 4/8 and ‘mop yarn’ which is an 8/8 equivalent count (more accurately 4/2/8 if you really want to split hairs).

But, US 8/2 cotton is in no way the same as the Canadian 2/8 yarn – other than having the same number of yards per pound (approximately – remember that the yards per pound given are only ever an approximation).

In my rather broad and deep yarn stash, I have some cones of cotton yarn given to me by a friend that are labelled 16/2.  When I got them, I gave them the ‘snap’ test to see if they were strong enough for warp and decided that they would make me much happier as weft.  When I started to use this yarn for weft, I noticed that it created quite a lot of fibre dust on my loom and around it as well.  I now use a filtered fan when I weave with it to prevent – as much as possible – breathing it in as well as having it drift through the rest of the house.

One of the tools in my weaving kit is a digital microscope.  It doesn’t enlarge as much as I would like, but it does give valuable information about yarns.

2/16 and 16/2 cotton yarn
2/16 and 16/2 cotton

The rust-brown yarn is the Canadian yarn while the blue/green is from the US.  

In spite of having the same count, the blue/green is apparently thicker than the other yarn.

This is because they have been prepared for and spun differently.  The rust is made from longer fibres that have been combed so that they are parallel, then given a fairly tight twist in both the single and the ply.  The blue has been open end spun which means the fibres are generally shorter than those used for ring spun yarns, and they are spun from the cloud so the fibres are disorganized.  The ply twist is much lower than the ring spun yarn.

As well as being physically larger, there is a lot more loose fibre sticking out of the yarn.  The open end spun yarn is loftier, with more air in it and it is weaker than the ring spun yarn.

It is also, however, more absorbent than the ring spun yarn.  

I am using the 2/16 quality of cotton for warp and using the 16/2 quality of cotton for weft for weaving tea towels.  This way I have the strength of the 2/16 and the absorbency of the 16/2 cotton.

Another reason for yarns with the same count being different is the density of the fibre.  Tencel is a regenerated cellulose fibre (rayon) and comes in 2/8 (or 8/2) size and has the same yards per pound as a 2/8 cotton.  However, because rayon is more dense than cotton, it is thinner than the cotton – the fibres are smoother and slippery-er, therefore using Tencel at the same density (epi) as cotton of the same count isn’t necessarily going to give the results desired.

Tencel and cotton yarns
Tencel and cotton

Since the Tencel is physically thinner than the cotton and it is slippery using 24 for twill (which is pretty standard for 2/8 cotton woven in twill), it may produce a cloth that isn’t as stable as you would like.  Tencel may be better at 27 or 28 epi depending on the weave structure and the weft being used.

When it comes to wool, both types of preparation are available.  Harrisville Tweed is carded and spun so that it is lofty with lots of air in it.  Trapped air is good insulation and Harrisville Tweed has been created with fulling as part of the wet finishing process being expected.  Worsted wool yarns however are made from fibres that have been combed so that their fibres are largely parallel and given a firmer twist (usually!).  The resulting yarns are generally stronger, denser, and have fewer loose ends sticking out so they feel smoother next to the skin.  For a true worsted quality cloth, zero fulling is applied so the cloth needs to be woven more densely to begin with because no stability will be received from fulling.

As part of the wet finishing a good hard press is applied to provide additional stability from being compressed together, warp and weft.

Harrisville Tweed and Gist Array yarns
Harrisville Tweed and Gist Array

A worsted cloth will not be as insulating as a woolen cloth but it will wear well and resist abrasion better.  It will not pill as much as a woolen cloth.

These differences are some of the reasons it is so difficult to give definitive answers to weaving questions.  How many epi will depend on a number of factors:  

  • How lofty is the yarn?
  • How slippery is the yarn?
  • What weave structure will be used?
  • What wet finishing processes will be applied?
  • What job is the cloth to perform?
  • How wide will the warp be?  The narrower the warp, the easier it is to beat the weft into place and why sometimes the epi between a narrow warp and a wide one needs to be adjusted to create the same quality of cloth.

Results may vary depending on the loom being used.  One with a heavy beater will likely beat the weft in more easily than a loom with a lighter beater.  One weaver may just have a lighter touch than another one.

How to tell?  I begin with a ruler wrap.  Some people do this loosely, I tend to do it with tension.  A lofty yarn will thin when tension is applied and a yarn with lots of elasticity will also become thinner.  It’s a good idea to understand that when the warp comes off tension the yarn will return to it’s untensioned state.  The weaver has to make allowances for this kind of change or wind up with a cloth that is either weft faced or very dense.

If the yarn is new to me I will weave a sample warp to test the epi and weave structure, and even wet finish it to make sure the finished result is close to what I want.

Once all that is done, I examine the cloth and decide how to proceed with my project.  Do I need to change anything?  Will the warp be a lot wider than my test sample?  If so, I might reduce the epi somewhat.

Only once I’ve done this research will I make up my mind and begin to work on my project.



The count is based on X number of yards per pound to give the value for ‘1’.  The different sizes are based on changing the thickness of the yarn spun from one pound of that fibre, therefore changing the number of yards that can be spun from one pound of the fibre.

  • Cotton:  840 yards
  • Linen:  300 yards 
  • Wool – worsted:  560 yards
  • Wool – woolen: may vary depending on the location of the mill – Yorkshire count is 256 yards
  • US count for woolen (runs): 1600 yards
    woolen (cuts): 300 yards
  • Spun silk:  840 yards (but differences in how the fibre is prepared will mean differences in the count system used)


  • Denier numbering was originally used for silk and regenerated fibres. 
    The larger the number the heavier the yarn.  The system is based on the number of grams per 9000 meters of yarn.
  • Tex numbering is applied to all yarns in the same way.
    The number indicates how many grams 1000 meters of yarn weighs.
  • Nm (or metrical numbering) is applied to all yarns.
    The number gives how many meters of a yarn are in one gram.

Join Laura at our A Good Yarn Live Lecture, part of the Fundamentals of Weaving series, taking place May 4, 2022 at 12pm PDT!

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