Measurements and terms can vary by country.
I’ll just give you enough information to get started.
I’ll explain things using US measurements. I know metric measurements are much easier to calculate, but since I live in the US, I’ll do it the hard way.
Let’s get started!
The size refers to how many yards of the fiber it takes to make 1 pound of the yarn. This is called the yarn count.
For cotton, silk, and rayon:
Size 1 means there are 840 yards of the yarn in 1 pound.
Size 3 means there are 2520 yards of the yarn in 1 pound. (3 x 840)
Size 5 means there are 4,200 yards of the yarn in 1 pound. (4 x 840)
Size 10 means there are 8,400 yards of the yarn in 1 pound. (10 x 840)
Size 20 means there are 16,800 yards of the yarn in 1 pound. (20 x 840)
The larger the size number, the finer the yarn.
1-ply is also called single because there is only one strand.
Singles are usually delicate and are used in the weft when weaving.
(the weft is the yarn that goes back and forth across your loom.)
Roving is definitely a single yarn, it is meant for spinning into yarn, and when weavers put it into their work, they know it’s mostly for decoration.
2-ply yarn is nice and soft, yet more durable than 1-ply.
When you see yarn labeled 3/2 that means it’s a Size 3 yarn with 2-plies.
They are typical sizes you’ll encounter when you’re shopping around.
Warp Yarn (the yarn that goes up and down on the loom)
The warp threads for any project need to be strung up tight, especially when you’re weaving a tapestry. You beat on those warp threads a lot, so it’s a good idea to choose a smooth, strong yarn, at least 3/2 is best.
Generally, the more plies, or strands, the stronger your yarn will be, but a finer yarn can still be very strong because there will be more twists per inch. Sewing thread is fine, yet quite strong.
A big factor in strength is the type of fiber the yarn is made of… which is another subject!
Go here to read more about fibers.
It’s nice to use soft yarns for the weft, but you still need to think about the end product.
If it will hang on the wall, or get little handling, just use whatever you want, but if you plan to wash it a lot, or it will get played with, use a stronger yarn.
Wool, worsted wool, and linen have different yarn counts than cotton, but they follow the same size of yarn/number of strands rule.
There’s lots more to yarn size, and different ways to calculate what you need.
When you’re weaving little tapestries, it’s easy and fun to just use odds and ends, but as you progress, you might want to tackle larger projects, and even learn to use a table or floor loom. I hope you do, and I’ll be here to help you!
Go to Craft Yarn Council for lots more information.
Fiber Hound Yarns also has an excellent blog post to help you understand yarn weights.
Handbook of Timesaving Tips for Weaver, Spinners, and Dyers
I referred to this little gem of a book often while I wrote this post.
It’s simply a book of lists and explanations of yarn terms, measurements, and guides for planning your weaving projects. Nothing fancy, just a great reference.
It might be small, but worth every penny. I’ve had my copy since 1985, and the reference tables are timeless. It explains all types of yarns and fibers and how to plan them into your weaving projects. The last update was 2013, so it’s just as relevant now as ever.
If you click the image, you’ll be taken to Amazon, I receive a small compensation from Amazon when you do. You can probably find it at most weaving shops, too.
April 29, 2018
This is such a useful post, Lucy. I know when I first started weaving, this was a bit of a mystery to me! Even so, I learned a couple of things in this post that I didn’t know before, so thank you! And thanks for the tip about the Handbook – going to check this one out.
June 16, 2020
Math isn’t my favorite subject either, I’m so happy this helped you understand!
Thank you, thanks you, thank you. Many forums have tried to explain this whole weaving yarn versus knitting, crocheting yarn/thread difference and you finally got me to understand. Math is not my strong suit, so, the pictures helped me to understand the concept of the number of yards to make a pound and what that would ultimately mean with regard to how fat or thin the yarn/thread would be. Such formulas are not abundantly clear to the math-challenged individual. Thank you for speaking to the lowest common denominator of us out here.
May 09, 2020
Thank you for this. It was so very helpful.
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