Yarn Weight: It’s Not Just a Number!

Welcome back to our ongoing blog series on Mastering Yarn. Over the last two weeks we’ve discussed many of the aesthetic and functional qualities of yarn and how they affect the big picture- your finished project. Now we’re ready to talk about the properties that we look at when selecting a yarn to get the results you want. This week it’s yarn weight!


Yarn weight is often the very first thing we look at when choosing yarn for a specific pattern. It’s absolutely crucial to achieving the correct fit, but it affects more than that- weight can influence the hand, drape, warmth, and other qualities of a yarn.


From left to right: a super bulky, a DK, and a lace yarn are visibly different weights; their qualities will be noticeably different as well.

What is Weight?

When we talk about weight, we’re referring to the overall thickness of the yarn. Seems pretty straightforward, right? For example, view the varying thicknesses of the yarns below.


From left to right: Super bulky, chunky, worsted, DK, fingering, and lace weight yarns.

Occasionally you’ll see or hear a yarn’s weight referred to by the number of plies the yarn has (for example 2-ply or 4-ply; the more plies, the thicker the yarn), but this has become an outdated way to describe weight. Plies are the small strands which are twisted together to form the yarn. Today, yarns may include a single ply or many- but they do not necessarily indicate a yarn’s weight, only its structure. You can see this in the photo below: the yarn on the left in only a single ply, but it is much thicker than the yarn on the right which contains 8 plies.


The yarn on the left is a single ply, bulky weight; the yarn on the right is an 8-ply fingering weight.

It’s also important not to confuse weight with gauge. Gauge is a measurement used for a knitted fabric, not a strand of yarn- it refers to the number of stitches per inch. Yarn weight is very closely related to gauge, of course- but gauge also depends on needle size, fiber content, structure, stitch pattern, the material the needle is made out of, the unique style of the knitter, even the knitter’s mood! The same yarn may be knitted at a wide range of gauges. In the photo below, two very different yarns are knitted at the same gauge – 4.5 sts per inch. So while gauge is a good starting point when selecting a yarn, it’s not always a perfect indicator of the weight you’re looking for.


In this case, an aran weight knitted on a size 5 needle and a sport weight knitted on a size 10 yield the same gauge: 4.5 sts per inch


To better understand weight, knitters have gradually developed categories with very general guidelines. These guidelines have changed over time- they once focused on plies, they often include a recommended gauge (but it’s only a suggestion), and now more and more manufacturers use numbers to indicate weight. Yarn weight is still not an exact science, but it is easier than ever to evaluate a yarn’s weight using these excellent, up-to-date Craft Yarn Council Standards and Guidelines. Feel free to download this PDF and keep it in your knitting bag- it’s a wonderful reference!

Since I couldn’t explain all the different weights of yarn any more beautifully than the Craft Yarn Council, that’s it for today! I challenge you to experiment with weight this week. Try swatching with different weights and feel how the fabric changes- pay attention to its softness, flexibility, stretch, sturdiness, warmth, etc.  Let us know what you discover!

Thanks again for reading. Happy knitting!




6 Comments (+add yours?)

  1. Christine Reese
    Aug 31, 2016 @ 13:23:35

    Very interesting, thank you!



  2. Kathy kithcart
    Aug 31, 2016 @ 15:17:08

    Very good article. You explained that so well. Thanks



  3. Gail
    Aug 31, 2016 @ 15:20:28

    Another great blog by you all, thanks for the PDF guidelines. It will be a very useful tool. I already have it printed and in my yarn bag.



  4. Trackback: Week 3: Fiber Content- Thinking Outside the Flock | The Yarn Patch
  5. Trackback: Week 4: Yarn Structure- A Twisted Tale | The Yarn Patch
  6. Trackback: Week 6: Putting It All Together- How to Read a Yarn Label | The Yarn Patch

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