Whether you’re new to needlecraft or an experienced knitter with a bag full of mystery yarn, it’s important to know the weight of your yarn before starting any project. It’s often difficult to know what kind of yarn to use, and there are so many factors to consider. Understanding yarn weight and how it figures into the finished project is just one aspect of planning a knitting or crochet project.

If you’re new to knitting or crochet and anxious to get started on your first pattern, you’ll note that the instructions often specify a particular weight of yarn to use. Following the instructions impacts the quality of your finished project. And yarn labels can be pretty confusing if you’re new to crafting with yarn.

Experienced knitters are known to horde a skein of wool or two, often left over from other projects or inherited from friends. Before knowing how to best use it, and if you have enough of it, you’ll need to know the weight of your yarn and the yardage as well. You’ll need to learn a few tricks to figure out the weight and length of your leftover yarn so you can make the most of your crafting dollars.

What is Yarn Weight?

The term yarn weight refers to the thickness of the yarn. Both knitting and crochet patterns use a variety of yarn thicknesses, and choosing the right weight will determine more than how your completed project looks and feels. It also determines how much yarn it will take to finish and even how long it will take.

There isn’t a worldwide industry standard, but most yarn manufacturers and pattern books in the United States are increasingly following the standards of the Craft Yarn Council of America. Their reference chart helps you find the right thickness and needle size for your pattern.

Understanding Yarn Ply

Interestingly enough, although crafters in Australia and the UK often refer to yarn weight by ply, the ply doesn’t affect the weight. It’s a bit of a holdover from the days when people made yarn by hand, and the number of plies gave a better indication of the thickness. And the terminology differs from country to country, which can make it all the more confusing.

Also, the plies in your yarn can be thin and fine, or thick and chunky. It’s the size of the individual plies that determine the yarn’s overall weight or thickness, rather than their number. A three-ply yarn can still be much thinner than a bulky yarn of only two plies. So, we’ll be using the U.S. standard in this article.

Reading the Yarn Label

It seems obvious, but one way to know the weight of your yarn is to check the label. However, these labels can be hard to decipher. On every skein of yarn in your local craft or department store, you’ll find a paper label. On this, you’ll see graphic icons that show you the yarn weight, a gauge for knitting, a gauge for crochet, and care instructions. The video below will help you make sense of these graphics.

Understanding the yarn gauge

Each pattern you use to knit or crochet will recommend a gauge for achieving the right tension in your stitches for the project. The gauge is crucial when knitting garments in particular because it refers to the number of stitches per 4-inch square. If you want your knitted garments to fit, you’ll have to match the number of stitches to the number of inches needed for the clothing item. To choose the right yarn, you can reference the gauge icon on the skein label. It indicates the number of stitches and rows you’ll get for a 4-inch square with that yarn using the needle or hook size shown in the graphic.

Common Yarn Weights

The Craft Yarn Council established their standard yarn weight system by defining the yarn weight by the number of stitches you can get from it in a 4-inch square. The council categorizes these weights from 0 to 7 — the finest to the thickest, respectively.

0 Lace

Lace is the finest and thinnest yarn you’ll find. As the name implies, you use it to make lace. Generally, you’ll use a U.S. size 000 to 1 needle when working with it. For making open lacework, you may use a larger needle or specialized needles. The gauge for this weight is 33 to 40 stockinet stitches and 32 to 42 double crochet stitches per 4-inch row.

1 Superfine

Also called baby-weight or fingering, this fine, thin yarn is for making baby garments and other lightweight items. You’ll find a US 1 to 3 size needle works best with this weight. When checking the gauge on your pattern, you can expect 33 to 40 stockinet stitches or 21 to 32 single crochet stitches per 4 inches using superfine yarn.

2 Fine weight

Also known as sport weight, fine weight yarn is commonly used for thin sweaters and baby clothes. You’ll typically use a U.S. 3 to 6 size needle for this weight. You’ll get 23 to 26 stockinet stitches or 16 to 20 single crochet in every 4-inch row.

3 Light weight

Also referred to as DK worsted, this is a commonly used yarn weight for a wide range of projects, including sweaters, scarves, and other garments. Generally, you’ll use a U.S. size 5 to 7 size needle when knitting with DK weight yarn. For every 4-inch row, you’ll get 21 to 24 stockinet stitches when knitting and about 12-17 single stitches for crochet.

4 Medium weight

Also referred to as worsted weight, you’ll find that many patterns for winter sweaters, blankets, and outdoor gear for cold temperatures recommend this weight. Using a size U.S. 7 to 9 needle, expect to get 16-20 stockinet stitches or 11-14 single crochet stitches per 4 inches with worsted weight.

5 Bulky weight

Some call it chunky weight, and it’s the right thickness for ski sweaters, rugs, blankets, and other crafts. You will need a U.S. size 10 or 11 needle to work with this thick wool. Expect 12 to 15 stockinet stitches for every 4 inches when knitting or 8 to 11 single crochet stitches for the same length.

6 Super bulky

Super bulky weight yarn requires a U.S. size 13 to 15 needle. Knitters use it for heavy blankets, rugs, and thick jackets. You’ll use 7 to 11 stockinet stitches or 7-9 single crochet stitches to achieve 4 inches of finished length.

7 Jumbo

Jumbo is the heaviest weight you’ll find to purchase, and you’ll need a U.S. size 17 or larger needle. It takes 6 or fewer stockinet or single crochet stitches to finish 4 inches of your project.

Calculate the WPI to Know the Weight of Your Yarn

What about that mysterious skein you found at the bottom of your crafting basket? If you’re wondering what the weight is and what you can use it for, try some of these tricks below.

Wraps Per Inch method

By figuring out how many times your yarn wraps around a standard pencil, you can know the weight of your yarn. This is known as the wraps per inch (WPI) method, and you may even see some balled yarns use this as a weight indicator.

  1. Grab a pencil and a ruler.
  2. Carefully wrap the yarn around the pencil so that each wrap touches, but doesn’t overlap.
  3. Make sure you don’t wrap it too tightly, or it won’t be accurate.
  4. Measure the pencil against your ruler and count the number of wraps that make one inch.
  5. Use the chart below to know the weight of your mystery yarn:
  • 0 / Lace: 35 or more WPI
  • 1 / Superfine: 19 to 22 WPI
  • 2 / Fine: 15 to 18 WPI
  • 3 / Light weight: 12 to 14 WPI
  • 4 / Medium weight: 9 to 11 WPI
  • 5 / Bulky weight: 7 to 8 WPI
  • 6 / Super Bulky weight: less than 6 WPI

Using the Actual Weight to Determine Yarn Length

Your knitting or crochet pattern may specify a yarn type and how much you’ll need to purchase in yardage. However, if you’re dealing with mystery balls of yarn, you may have no idea if you have enough. You’ll be relieved to know that if you know the weight of your yarn, you can find out how many yards you have. That way, you’ll know if you have enough before you start your project.

For this method, you’ll need your yarn, a cardboard box, and a digital scale. The first and most important thing you’ll need to know is how much a set length weighs. You can start by weighing a sample and then doing the math.

  1. Cut a sample of your yarn exactly 10 yards long.
  2. Put your box on the scale and zero it out following the manufacturer’s directions.
  3. Place your 10-yard sample in the box and weigh it.
  4. Divide the resulting gram measurement by the 10 yards you weighed.
  5. Now you know the weight of your yarn per yard. We’ll call that “X.”
  6. Now, place all your mystery yarn into the box and weigh it.
  7. Take the total weight in grams and divide by X.
  8. Now you know the yardage of your leftover yarn and can plan your future projects in confidence.

For example, let’s say that a 10-yard length of yarn weighs 20 grams. That means that each yard weighs 2 grams. So, the answer to 5 above is 2. And let’s say that when you weigh all your yarn, you get 1,200 grams. Divide that total weight by X (2), and you’ll see that you have 600 yards of yarn ready for your next knitting project.

If you’re lucky enough to have the labels for your yarn still, but don’t have any idea if you have enough yardage left over for your project, watch the video below to help you calculate it:

Why It’s Important to Know the Weight of Your Yarn

When referring to the thickness of your yarn, it’s essential to get the weight right for the project you’re working on. For blankets and throws, you’ll want heavyweight wool to make sure your project yields warm and toasty results. Naturally, you’ll want to find knitting patterns for heavyweight skeins of yarn.

When you’re making garments, using the wrong weight means it won’t fit properly. The gauge of the pattern and the yarn need to sync together to make sure that your structured projects fit correctly. Otherwise, your sweater will end up too big or too small.

If you know the weight of your yarn, you’ll have more creative freedom. You’ll find it easier to substitute the yarn recommended by your pattern if you know the weight and how it relates to the gauge. Some patterns might call for expensive wool that’s out of your budget range. But now that you know how to figure out the weight and understand the gauge, you can choose a more affordable acrylic yarn instead.

If you know any little tricks for figuring out how to use leftover and mystery yarns, or how to convert needle sizes to handle different yarn weights, let us know in the comments below.


Featured image CC0, by Tim Savage, via Pexels.