Yarn Weight Conversion Chart – Don’t Be Such A Square

You’ve heard of yarn weights before, but did you know they vary from brand to brand? What does this mean for you? How much yarn should I buy? And why would someone want to buy yarn in different weights?

To make sure you get the correct amount of yarn, you’ll need to know the difference between the different types of yarn.

If you’re new to knitting, you might be wondering why anyone would want to knit with heavier yarn.

Well, heavy yarn makes your knitted items stronger and less likely to stretch out over time. 

Yarn Weight Conversion Chart - Don't Be Such A Square

Moreover, yarn weight is not always talking about solid weight, but surprisingly is centered on thickness.

We look at yarn weight in closer detail in this article and most importantly, a yarn conversion chart to help make things as easy as possible when it comes to your next sewing project!

Yarn Weight

When you start learning about knitting, you might notice that there are different kinds of yarn available.

Some of these are called sportswear yarns because they’re used for making sweaters and other garments.

These are usually made from acrylic, nylon, or cotton.

They come in many different weights, such as 4 oz (113 g) or 6 oz (170 g). The higher the number, the thicker the yarn.

If you’re just starting, then you probably don’t have any idea what kind of sweater you’d like to knit.

That’s okay, though, because you can always choose a lighter-weight yarn to begin with and go from there.

It will still give you something nice to wear, but it won’t weigh you down. 

Every sewing project requires yarn, and the right weight is so important for producing those great final results.

You’ll also need the right tools such as a knitting needle or crochet hook to obtain the right gauge.

Knowing your yarn weight on top of this makes it much easier to choose a yarn that will work successfully with your project.

RELATED: Best Oversized Yarns For Knitting A Chunky Blanket

Why Is It So Important?

  • Yarn weight is so important because it affects gauge/tension
  • Yarn weight can help you to work out how much you need for one project
  • Knowing yarn weight does make it much easier and simpler to switch out the yarn that is suggested in a pattern guide
  • Being able to convert between yard systems makes it a lot easier to shop around for yarn in other parts of the globe, when you are traveling or have moved home
  • The yarn weight gives a hint of which knitting needle size you need 

To help you out, we have included a handy weight conversion chart below!

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(Yarn Weight Chart)- miriamfelton.com

This chat shows how yarn is split into categories based on its weight (thickness).

In the knitting world, there are several systems, and this cheat sheet should not only help you with thickness, but also needle sizes, etc.

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So What Exactly Is Yarn Weight?

The term “yarn weight” refers to the thickness of the yarn. The thickness of a yarn determines its strength and durability.

When you knit, you use the yarn to create stitches by using a knitting needle or crochet hooks. The size of the needles and hooks determines the size of the stitches.

It’s important to know yarn weight as it will determine how the project will turn out, and how it will look and feel.

It will also determine how long it will take you to reach the finish line. The thicker/heavier the yarn, the longer the project will take.

Thicker yarns are much better when used to make blankets or warm sweaters, whereas thinner types are better suited for delicate shawls and baby clothing.

There are two main categories of yarn: worsted and light. The differences between the two are quite significant.

Light yarn is thinner than worsted yarn. It has a lower density and therefore takes up less space.

This means that you can knit more rows per inch. However, if you compare the same weight of both yarns, the light yarn will take longer to knit.

Worsted yarn is thicker than light yarn. It has a higher density and therefore takes up more space. This means that the knitter can knit fewer rows per inch.

However, the knitter can produce a larger stitch size.

What Are The Different Types Of Yarn?

There are many different types of yarn on the market and the characteristics depend on the type of fiber used and how it was spun.

For example, wool is made up of long strands of protein called keratin, while cotton is made up of short strands of cellulose.

Yarn Fibers

There are three main types of fabrics.

These range from animal fibers which include all kinds of wool and types of silk, to plant fibers including cotton, linen, flax, and hemp, and man-made or synthetic fibers including acrylic and rayon. 

Spinning processes create different structures for yarns. Single-ply yarns are softer and have fewer stitch definitions than multi-ply yarns.

This makes single-ply yarns much softer and more comfortable to wear.

Single Ply vs Multi Plied Yarns

Multi-ply yarns are produced by spinning multiple filaments together. They offer excellent performance properties such as high strength and abrasion resistance.

They are generally very durable.

Single-ply yarns are produced by twisting one filament around another. This creates a stronger structure. They are usually soft and flexible.

As we have mentioned, different spinning processes result in different yarns.

Each process produces a unique yarn, whether that is single or multiply. Both are used for different purposes.

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Yarn Standards

There are several different standards for yarns. In the United States, standard yarn weights come from the American Yarn Council (AYC), using only a couple of numbers and factors.

Whereas the famous kitting and crochet community known as Ravelry uses a system with a lot more categories added. 

In the UK and New Zealand, they use a system that is based on the number of piles that yarn has.

You can also determine the WPI which means wrap per inch and this will work out the yarn weight based on how many wraps of one yarn fits one inch.

Craft Yarn Council

As yarn weight is so complicated, the Craft Yarn Council of America tries its best to make it simpler for people using a system of standards.

The standards from the council use different categories to sort the yarn depending on the thickness. It means 0 is the thinnest yarn and 7 is the thickest.

  • 0 is for Lace
  • 1 is for Super Fine
  • 2 is for Fine
  • 3 is for Light
  • 4 is for Medium
  • 5 is for Bulky
  • 6 is for Super Bulky
  • 7 is for Jumbo

This system allows you to substitute yarn with any other in the same category, wherever you are in the world.

Many global manufacturers use the yarn standards from the council and you will find them on the label in most cases.

If you have lost the label, you can also use WPI.

This stands for Wrap Per Inch and can help you work out the yarn weight and which needles to use.

It is a method to decide which category your yarn falls in, and we will explore it in the next section.

Determining Yarn Weight With WPI

Determining Yarn Weight With WPI

Wrap Per Inch is a way of measuring the thickness of the yarn.

The higher the number, the thicker the yarn.

To decide on the Wrap Per Inch, you need to have a ruler or a tape measure and something to wrap your yarn with such as a knitting needle or a pen. You could use anything that resembles a cylinder.


  • Wrap your yarn around a knitting needle with a pen or whatever you are using for a few inches.
  • Ensure your yarn is wrapped without crossing or leaving gaps between strands.
  • Measure an inch that equals around 2.5 cm, and count the number of wraps in that space. Measure a few different places.
  • When you know the WPI, use the cheat sheet we have included above and compare your WPI.
  • WPI can depend on how much you wrap the yarn and you can always make a swatch.

Needle Sizes/Yarn Weights

The needle sizes that are in the cheat sheet are only suggested sizes and every knitter needs to have their unique way of knitting.

Some knit much more loosely which requires a much smaller size, but some knit a lot tighter and need much larger needles.

It will depend on the result you are aiming for.

Knitting lace with yarn, for example, would not give you that airy lace filled with well-defined holes and stitch patterns. Instead, you will need to go up a few needle sizes.

Yarn Weight/Ply

A lot of countries use ply as a rough guide for the yarn weight. These countries include Australia, New Zealand, and the UK.

Yarns are full of fibers that are spun together to make them tougher and a lot smoother.

Fibers are spun in single strands at first, using an S or a Z-twist.

Following this, a few more strands are spun together in different directions and this is what makes the yarn. If the first strands are S-twists, the yarn needs to be Z-twisted.

This twisting process of individual strands together is known as ply yarn.

But a single strand of yarn is called a single as ply is the process of twisting strands together. 2-ply yarn is made from twisting together two singles, one 3-ply using three singles, etc.

Plied yarn is much more durable and a lot stronger than singles which makes the final product last much longer.

As we have mentioned before in the article, some nations use ply for yarn weights and it can say a lot about the thickness and quality of the yarn.

However, ply is not equal to the yarn thickness, but instead tells us how many singles get plied together. This does not equal thickness.

For example, a 4-ply can be much thinner than a 2-ply, but this will depend on how thick the singles are and how tight they are after they have been spun.

How To Knit With Yarn Held Double

Hold two strands of yarn together and knit or crochet with both of them as if they were a single strand.

Don’t worry about the difference in yarn weight, but having a simple understanding of how to combine yarn strands can make it a lot easier to convert between weights, making it easier to substitute yarns for patterns.

For instance, if your pattern wants you to use a held double, you can work out the weights that equal the correct weight, and now you have plenty of patterns to choose from.

This is similar to if your pattern calls for a thicker yarn but you don’t have thicker yarn in the house.

You can work out how to put together two thinner strands that will eventually equal the right weight.

RELATED: How Many Skeins of Yarn Do You Need to Crochet a Blanket?

Why Does My Pattern Say I Should Use Different Size Needles?

Sometimes when you’re working out the gauge of a project, you’ll find yourself needing to change the size of your needles.

The reason why you might need to do this is that the pattern asks you to knit with a ribbed brim for example.

When you knit a ribbed brim, you need to increase the number of stitches by knitting into the ribs.

You also need to decrease the number of stitches when you reach the end of the row so that you create the shape of the brim.

When you’re knitting a hat, you usually start with a smaller needle size (usually US 1) and then gradually increase until you reach the largest needle size needed to complete the pattern.

So if you’re working out the correct gauge for a hat, you would start with a small needle size and then work up to the next larger needle size.

You may notice that the pattern doesn’t tell you exactly what size needle to use.

This is because there’s no set rule for this. It depends on the type of fabric you’re knitting and the style of the garment.

You can always ask the person who wrote the pattern if they know what size needle they used.

If they didn’t specify, you could try using a few different sizes and see which one works best for you.

Frequently Asked Questions

What Do You Need To Make A Good Crochet Project?

To knit or crochet, you need to have yarn, and for most projects, the right yarn weight is an important ingredient for making sure your efforts are rewarded with a result that stands up to your expectations.

What Is Yarn Weight?

It’s actually about how thick the yarn is. The yarn weight – determines what projects the yarn is suitable for.

What Are The Characteristics Of Yarn?

The characteristics of yarn are dependent on the fiber it’s spun out of and how it’s spun.

What Are The Different Yarn Standards?

There are a few different yarn standards, but most standard yarn weights are from the yarn council.

What Is The Craft Yarn Council Of America?

Yarn weights can be quite confusing, therefore the Craft Yarn Council of America created a system of standards.

The CYCA is simply an organization that seeks to galvanize current and future crafting communities by supplying standards and information resources.

What Is The Difference Between Crochet And Knitting?

Crochet and knitting are very closely related, but there are differences between them. Knitting is done by creating loops of yarn while crocheting creates loops of thread.

Knitting is done with a pair of needles while crocheting is done with a hook.

Crochet has its terminology such as chain stitch, slip stitch, treble crochet, etc, whereas knitting uses terms such as cast on, bind off, purl, and knit.

Crochet and knitting can be combined to produce some really interesting results. For example, you can crochet a scarf and then knit the ends to create an entirely new item.

Final Thoughts

We hope after reading this article you understand everything you need to know about yarn weight and realize it doesn’t refer to the actual weight, but instead the thickness of the yarn. 

Remember, knowing about yarn weight makes it much easier and simpler to switch out the yarn that is suggested in a pattern guide, and so why not use this guide to familiarize yourself with it today!

Amanda Brown
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