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If you’re new to crochet and knitting, understanding yarn weights might just sound like another confusing topic to learn about. The reality is, though, that yarn weights can be very important. This is especially true when your pattern needs to come out to an exact size, such as with a clothing item. In this post, I’ll give you the basics of understanding yarn weights so that your next project will come out just right.
Understanding Yarn Weights
Walk down the aisle of your local craft store, and you’ll soon see that yarn comes in a huge range of thicknesses, from superfine lace yarn all the way to super thick jumbo yarns.
These different thicknesses of yarns are organized into categories, called yarn weights.
Generally speaking, yarn is divided into seven different yarn weight categories labeled with the numbers 0 through 7. These categories are (from 0-7): lace, super fine, fine, light, medium, bulky, super bulky, and jumbo.
Knitting and crochet patterns are designed with a certain weight of yarn, so it’s important to buy the right type. When shopping for yarn, you can find the yarn weight category written on the yarn label. The label will usually have the category number, and/or the category name that goes with the specific number.
How is Yarn Measured?
Although we say that yarn is classified into “weights,” we don’t organize it according to its actual scale weight (as in ounces or pounds). Instead, the term “yarn weight” actually refers to the thickness of the strand of yarn.
What Determines the Weight of Yarn?
A yarn’s weight is determined by measuring the diameter – or the thickness – of a strand of yarn. The most common way to measure a strand’s diameter is with a method called wraps per inch, or WPI.
WPI is exactly what it sounds like – take a strand of yarn and wrap it around a ruler until one inch is covered. The number of times that the yarn wraps around in one inch is the WPI.
For example, if your yarn wraps around the ruler ten times in one inch, then your yarn has a WPI of 10.
Yarn Weight Categories
To help crafters select the right yarns for their projects, the Craft Yarn Council has set up a system of guidelines that yarn manufacturers use to categorize their yarn.
The CYC standard yarn weight system has seven different categories, numbered from 0 to 7. The lower numbers indicate lighter-weight yarns, while the higher numbers indicate heavier-weight yarns.
CYC Yarn Weight Standards
Here are the categories and the types of yarn in each category as indicated by the CYC (Craft Yarn Council).
Lace weight yarns are the lightest weight of yarns, and are usually used for delicate projects such as doilies, shawls, and intricate lace patterns.
1 Super Fine
Super fine weight yarns are also known as fingering weight or baby weight yarns. They’re slightly heavier than lace weight yarns, and are typically used for projects such as socks, baby clothes, and lightweight scarves.
Fine weight yarns are also known as sport weight yarns. They’re slightly heavier than super fine weight yarns, and are typically used for projects such as sweaters, hats, and other lightweight clothing items.
Light weight yarns are also known as DK weight or double knitting yarns. DK yarns are slightly heavier than fine weight yarns, and are typically used for projects such as sweaters, hats, scarves, and baby clothes.
Medium-weight yarns are also known as worsted weight yarns or aran yarns. They’re slightly heavier than lightweight yarns, and are typically used for projects such as afghans, sweaters, and hats. I often think of worsted weight yarns as “all-purpose” yarns, since you can use them for so many different types of projects.
Bulky weight yarns are also known as chunky weight yarns. They’re heavier than worsted weight yarns and are typically used for projects such as sweaters, hats, scarves, and blankets.
6 Super Bulky
Super bulky weight yarns are some of the heaviest yarns, and are typically used for projects such as hats, scarves, and blankets. It’s easy to learn how to knit with super bulky weight yarns, since it’s so easy to see the individual stitches.
Jumbo weight yarns are the heaviest weight of yarns, and are typically used for projects such as accessories and home decor projects, like blankets. These types of yarns are also used for arm-knitting projects.
Yarn Weight Symbol Chart
In addition to the names given to each category, the Craft Yarn Councils has designed a set of symbols to indicate the weight of yarn. These symbols can be found on the yarn labels of most commercially available yarns.
The following chart shows the seven different CYC yarn weight categories, along with their corresponding names, WPI, gauge, suggested needle and crochet hook sizes, and symbols.
|CYC Category||Common Names||Ply||WPI||Needle Sizes||Knit Gauge|
|Hook Sizes||Crochet Gauge|
|0 : Lace||Thread|
|30-40||000 to 1|
|Steel 6, 7, 8 or B-1|
(Steel 1.6-1.4mm or 2.25 mm)
|1 : Super Fine||Sock|
|4 ply||14-30||1 to 3|
|B-1 to E-4|
(2.25 – 3.5 mm)
|2 : Fine||Sport|
|5 ply||12-18||3 to 5|
|E-4 to 7|
(3.5 – 4.5 mm)
|3 : Light||DK|
|8 ply||11-15||5 to 7|
|7 to I-9|
(4.5 – 5.5 mm)
|10 ply||9-12||7 to 9|
|I-9 to K-10 1⁄2|
(5.5 – 6.5 mm)
|5 : Bulky||Chunky|
|12 ply||6-9||9 to 11|
|K-10 1⁄2 to M-13|
(6.5 – 9 mm)
|6 : Super Bulky||Super Bulky|
|14 ply||5-6||11 to 17|
|M-13 to Q|
(9 – 15 mm)
|7 : Jumbo||Jumbo|
|16 ply||1-4||17 and larger|
(12.75 mm and larger)
|6 sts and fewer||Q and larger|
(15 mm and larger)
|6 sts and fewer|
How Do I Tell What Weight My Yarn Is?
Usually, you can determine the weight of yarn by reading its label. Look for a number (0-7) or a weight category name.
On the other hand, avid crafters know that it’s common to end up with skeins of yarn that have no labels. Whether you accidentally threw the label away or you inherited the yarn from your grandmother, if you craft for long enough, you’ll surely find yourself with unlabeled yarn.
Fortunately, all is not lost. You can find out any yarn weight by using the wraps per inch (WPI) technique.
What is WPI?
As mentioned earlier, WPI (wraps per inch) is a common way to determine a yarn’s weight. Whether your yarn is missing its label or you simply want to check that the label is correct, using the WPI technique is easy and takes only a minute or two.
How to Measure Yarn Weight in “Wraps Per Inch”
To measure your yarn using WPI, you’ll need a ruler or a WPI tool.
Then, take your yarn and wrap it around your ruler or WPI tool. Wrap your yarn so that the strands lay flat next to each other without overlapping.
Continue wrapping until the stands of yarn cover one inch of the tool. When you are finished, count the number of wraps that fit into an inch. Compare the number of wraps per inch to the chart above to determine the yarn’s weight category.
Keep in mind that your results will vary depending on how tightly you wrap the yarn. That’s why it’s always important to work up a gauge swatch before starting a project.
What Does Ply Mean?
When talking about yarn weight, you’ll often hear terms like 4-ply yarn, 8-ply yarn, or 10-ply yarn. These terms refer to the number of strands that are twisted together to make the yarn.
In other words, ply is a measurement of how many strands of yarn are used to make one strand of yarn. A two-ply yarn is made of two strands twisted around one another. Three-ply is made of three strands, and a four-ply yarn is made of four strands.
How Does Ply Affect Yarn Weight?
In general, the higher the ply, the thicker the yarn will be. For example, 4-ply yarn is thinner than 8-ply yarn, which is thinner than 10-ply yarn.
However, it’s important to note that ply does not necessarily correspond with yarn weight or thickness. Some very chunky yarns are only two-ply (that is, they have two, thick strands). On the other hand, some multi-ply yarns are quite thin.
Ply vs. WPI
Ply is different from wraps per inch (WPI). WPI measures how many times a strand of yarn can be wrapped around an inch-long object like a pencil or ruler. Ply measures how many strands of yarn are used to make one strand of yarn.
Choosing the Right Yarn Weight for Your Project
When choosing the right weight of yarn for your project, there are a few things you’ll need to keep in mind. First, think about what kind of project you want to make. Do you want to make a sweater? A scarf? A blanket? The type of project you want to make will influence the weight of yarn you’ll need to use.
For example, lightweight yarns are used for delicate patterns, like shawls and socks. Medium-weight yarns are often used for sweaters and hats. And thicker yarns are often used for projects like chunky blankets and pillows.
Choosing the Right Hook and Needle Size
After you decide on the yarn weight you’ll need for your project, you’ll need to consider what size hook or needle to use.
In general, smaller hooks and needles are used for lighter yarns, while larger hooks and needles are used for heavier yarns. You can find recommended sizes in yarn weight chart above, or in this detailed crochet hook chart and comparison guide.
You can also find recommended hook and needle sizes are listed on the yarn label.
Tip: The recommended hook and needle sizes are just that – recommendations. Depending on how tightly or loosely you knit or crochet, you may need to use a different size hook or needle to get the same gauge as the pattern designer. Make a gauge swatch, and then decide whether you need to size up or down.
Why Yarn Weight Matters
Sometimes you can get away without worrying about your gauge or yarn weight. Some projects, like blankets, scarves, and hot pads will probably be just as functional even if they end up a few inches bigger or smaller than expected.
When you’re making other items, like socks and sweaters, you’ll want the finished measurement to be exact. Imagine spending hours making a beautiful piece of clothing and not having it fit! For projects like these, you’ll need to choose the correct yarn weight and needle/hook size to meet gauge.
Imagine you’re knitting or crocheting a 1-inch square. With a chunky yarn, you may only need 3 or 4 stitches to measure 1 inch. On the other hand, if you’re working with a very thin yarn, you may need 8 or 9 stitches to measure 1 inch. This is why it’s important to look at a pattern’s suggested yarn weight and to always make a gauge swatch before getting started.
Yarn weights are also important when you’re using more than one type of yarn for a project. For example, if you’re making squares for an afghan blanket, you’ll need every square to be the exact same size, no matter what yarn is used. In order to ensure consistency, you need to have a basic understanding of yarn weights.
Yarn Weights FAQ:
Here are some answers to commonly asked questions about understanding yarn weights.
Are all yarns in the same weight category the exact same weight?
Weight categories are extremely helpful for grouping different yarns. However, just because two yarns are in the same weight category does not necessarily mean that they’re the exact same weight. In fact, there can be significant variation even within a weight category.
The best way to find your yarn’s weight is by reading the yarn label or measuring its WPI. And again, if you’re making a garment or other project that needs to be an exact size, be sure to create a gauge swatch before getting started.
Is aran yarn the same as worsted yarn?
Both Aran and Worsted yarns are considered medium weight. Although they look similar, they are actually two different yarn weights.
Worsted weight yarn is slightly thinner and finer than Aran yarn. Aran weight yarn is generally a bit thicker.
The two are often interchangeable. Again, though, if the finished size is important, be sure to make a gauge swatch before substituting one for the other.
How do you substitute yarn weights?
The best way to substitute yarn weights is by using a yarn that has the same WPI. This ensures that your finished project will be the right size.
But, what should you do if you’re in a craft store, and can’t unravel the yarn to check its WPI or knit up a gauge swatch? In that case, the easiest way to choose a substitute yarn is to check the yards per ounce (meters per gram) measurement listed on the label. If the yards/oz (meters/g) measurement on the new yarn matches the yarn called for in the pattern, it will probably be a good substitute.
Tip: When substituting yarns, you’ll want to stick with the same type of fiber. This way, the yarn will still have the same characteristics that are needed for your particular pattern.
Even More About Yarn Crafts
For more information about yarn and fiber crafts, check out these related articles.
- How to Crochet: A Complete Guide for Beginners
- How to Knit: Complete Guide for Beginners
- Knitting vs. Crochet: What’s the difference, and which is easier?
- How to Macrame: Get Started with this Easy Beginner’s Guide
- How to Punch Needle: Complete Guide
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Tuesday 7th of March 2023
I have some crochet cotton that says it size is 6/4. I don’t know what that is. It looks like fingering weight but not sure. Can you translate?
Tuesday 7th of March 2023
Sure, weaving yarn is often described by that type of numbering system. The first number is the size of each ply, and the second number is how many plies the yarn has.
Fingering might be the right category, but I would recommend doing a WPI (wraps per inch) measurement to make sure.
Sunday 5th of February 2023
Hi Sarah, I am a beginner in crocheting. I have been crocheting for three weeks now and I am enjoying every moment of it. I just ran across this article and I love it. It was so helpful. Cheryl
Wednesday 7th of September 2022
I have no label on this ball of yarn. It weighs 8 oz & using your info it us 2 strands. I need a #4 weight yarn & one skein of 7 oz yarn to complete this child poncho. Will I have enough yarn to complete?
Wednesday 7th of September 2022
Hi Josie, It sounds like you need a category 4 yarn for your project, is that right? Can you try the WPI test to see what the thickness of your yarn is? The number of plies in the yarn is not a good way to determine what category it is.
Guide to DK Weight Yarn - Sarah Maker
Tuesday 9th of August 2022
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