The means of measuring yarn size seems to be a common source of confusion among knitters. Interestingly enough, it's one of the first things that must be mastered by weavers in order to get a warp on the loom.

About Yarn

Yarn Phobia

The fact is that while the systems may appear to be very different on the surface, they all accomplish the same thing and that is to identify yarn in terms of size and weight. Now before you go getting all excited, it's not quite that simple... but hopefully what seems to be a sea of inconsistencies will make a lot more sense by the time you've finished reading this article.

Yarn Weight

In recent years, some manufacturers have begun using standard symbols to categorize yarns in terms of its size. While this practice is becoming more common, it isn't what I would call widespread and you're likely to come across many labels that don't use the symbols.

Symbol	Description & Examples	Stitch Gauge For Stockinette Measured Over 4"
	Super-fine: sock, fingering, baby	27-32
	Fine: sport, baby	23-26
	Light: DK, light worsted	21-24
	Medium: worsted, afghan, aran	16-20
	Bulky: chunky, craft, rug	12-15
	Super-bulky: bulky, roving	6-11

Yarn Count

Yarn count, sometimes referred to as thread count, is the number of yards required to make one pound of size 1 cotton, linen or wool:

Contrary to what one might think, size 1 (or #1) is the largest possible size for a single strand of any fiber. A pound of #2 yarn contains twice the yardage of #1, but is half the diameter; #3 contains three times the yardage and is one-third the diameter.

It should be apparent at this point there are three factors that affect yards per pound (YPP):

• the type of fiber
• the number of plies
• the size of a single ply

Since the count system is mathematically accurate, it provides the foundation for identifying unlabelled yarn and calculating yarn factors that aren't listed on the label.

Given three of the four factors (count, size, plies and yards per pound), you can easily calculate the missing information:

This label identifies the yarn as a 3-ply #10 cotton at 2800 YPP.

A Brief Chat About Wool

• The most common wool systems used in the US are the cut system and the run system with the run system being the most common in all areas except Philadelphia.
• In the cut system, coarse yarns are 5 to 7 cut, medium yarns are 18 to 21 cut and fine yarns are 30 to 35 cut.
• In the run system, coarse yarns are 1 to 3 runs, medium yarns are 3 1/2 to 5 runs and fine yarns are 6 to 8 runs.

Wraps Per Inch (WPI)

Because it's easier to visualize the apparent size of a yarn from its WPI rather than its count or YPP, knowing how to determine WPI is an excellent tool for selecting new yarns or sorting your yarn stash.

I prefer determining WPI using a little tool I bought that is specifically designed for the purpose, but you can accomplish the same thing using a round pencil, broomstick handle or 6-inch piece of wooden dowel. Avoid wrapping your yarn around a flat ruler or stick -- the sharp edge may affect the wrap and result in an inaccurate WPI.

• Hold the pencil in one hand and use the thumb of the same hand to hold one end of the yarn against the pencil.
• Use the other hand to wind the yarn around the pencil making sure each "wrap" is laying next to the wrap before it without stretching the yarn. The yarn should wrap naturally around the pencil and should be no looser or no tighter than its unwrapped state.
• Once you have the pencil wrapped for at least 1 1/2", use a ruler to measure off a 1" section and count the number of wraps in 1".

Useful Tools

Electronic Kitchen Scale

WPI Tool

• Cut a narrow slit across one end.
• Drive a small brad about 1" away from the slit to mark where you're going to start your wrap.
• Make a permanent mark on the dowel exactly 1" away from the edge of the brad.

Thread the end of the yarn through the slit to secure it, turn the corner around the brad and start wrapping. Stop wrapping when the yarn is at the 1" mark. If you want a higher degree of accuracy, wrap 2-3 inches and divide the number of wraps by the length of the wrap.

You can also buy WPI tools from Nancy's Knit Knacks. It comes with a laminated card that lists the WPI for the six standard yarn weights. The tool and card are small enough to keep in a side pocket of your purse so you always have it with you when you're out and about.

McMorran Yarn Balance

A McMorran Yarn Balance can be used to quickly determine YPP with a pretty high degree of accuracy. You position the balance at the edge of a table and hang a small length of yarn over the arm of the balance. You snip tiny bits of yarn off the dangling ends until the arm is perfectly horizontal. Measure the piece of yarn that remains and multiply by 100 to determine YPP.

Name That Yarn

I find that the simplest way to identify a yarn is to start with YPP. If you don't have this information, you can use the McMorran balance mentioned above; or you can guestimate by measuring off a substantial amount of yarn (10-15 yards), weighing it and dividing the weight by the number of yards. Keep in mind that stretchy yarns need to be measured carefully in order to not skew the results. It may be useful to hang a yard stick on a wall and measure the yarn by letting it hang naturally.

Since yarn count is tied to the type of fiber, identification will be difficult if you don't know what kind of fiber you're dealing with. Fabric University has a great article on using the Burn Test to determine content. Keep in mind that the burn test may yield odd or inaccurate results if the yarn is a blend.

If you can figure out YPP and content, you're home free. Simply count the plies and use the tables and formulas described in this article to figure out everything else.

I recently discovered a cone of very fine yarn in my stash. I was pretty sure it was wool, but I did the burn test just to make sure. I then used my McMorran Yarn Balance to determine my yarn is 8200 YPP. I untwisted the end and learned that my yarn was a 2-ply. I assume my wool is either cut system or run system because I know it was manufactured in the US, so I also assume the count has to be 300 or 1600; I'm going to start with the run system because I'm pretty sure this yarn was manufactured by Dorr Woolen Mills in New Hampshire.

Going back to my formulas, I first calculate the yarn size since that's a definite unknown:

8200 ÷ 1600 x 2 = 10.25... since #11 would be an odd size, I decide my yarn is most likely #10. Now I'm going to use the other three formulas to check my work:

In the table below, you can see how close the numbers are between the formulas and the numbers I derived from my research. Since a difference of 2-3% is well within the margin of error, I decide my YPP is really closer to 8000 instead of 8200.

Copyright 2004, Brenda A. Bell Unless otherwise stated the content of this web site, including text, graphics and downloads, is the property of Brenda A. Bell and is protected by current copyright laws. It may be reproduced and redistributed free of charge in electronic or printed form provided that this copyright notice is included exactly as written. The content of this web site may not be sold, nor may it be included in any for-sale publication or product without the express permission of the author. All inquiries regarding copyright restrictions should be submitted via email to the . The "cat" graphic appearing at the top of all pages is owned by Microsoft Corporation and available for download from Microsoft Office Online.
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