The best guide to yarn weights

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Ply? wpi? Worsted? What does all that really mean?

Have you found yourself all tangled up in yarn weight issues? That makes us two.

So Fellow Knitters, it’s about time we take a grip on those yarn weights don’t you think?

As a bonus, I have created a yarn weight conversion chart to make things easier!

Why we should care about yarn weight

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

You also need to have the right tools, knitting needels or a crochet hook, in the right size to obtain the right gauge.

The best way to get all of the above to work together nicely is to know how they affect each other. Knowing your yarn weight makes it easier to choose a yarn that will work for your project.

So, yarn weight is an important ingredient in knitting, but why?

  • It affects gauge (or tension as some of us like to say)
  • Yarn weight can help you determine how much yarn you need for a project.
  • Knowing yarn weights does it easier to switch out the yarn suggested in a pattern.
  • Being able to convert between different systems for yarn weight makes it easy to shop yarn from other parts of the world.
  • The yarn weight gives a hint of which size of knitting needles that’s suitable.

So, do you have to learn all the systems for yarn weight? No, not at all! All you need is this cheat sheet I’ve made for you.
Be sure to pin it for later!

Your Best Guide to Yarn weights – a cheat sheet for knitters! Please click on the image to open it as a pdf that you can zoom in, download or print.

What is yarn weight

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Yarn weight – it may sound like it’s all about the weight of a yarn ball. But no, it’s actually about how thick the yarn is.

The thickness of the yarn – the yarn weight – determines what projects the yarn is suitable for.

The thickness of the yarn affects your projects in a couple of ways

  • How your project will look and feel. 
  • How long it will take you to get to the finish line. 

If you pick a heavy/thick yarn you will complete your project faster, but you also have to think about the result.

For example, a thicker yarn may be suitable for a blanket or a warm sweater for an adult. While a thinner yarn is a better choice for delicate shawls or baby clothing.

Yarn is divided into different categories depending on their thickness – weight. And, as always in the knitting world, there isn’t just one system but several.

In the cheat sheet above I’ve gathered the most usual ones alongside the needle sizes and gauge recommended for each weight.

Different kind off yarns

There are a bunch off different kinds of yarn. The characteristics of yarn are depending on the fiber it’s spun out of and how it’s spun.

I will go through this subject briefly here. If you are interested in yarn fibers and their characteristics, please read more here: How to pick yarn for my knitting project?

Yarn fibers

There are three main categories of fibers:

  • Animal fibers including all kind of wool and silk
  • Plant fibers such as cotton, flax, and hemp
  • Manmade/synthetic fibers such as acrylic and rayon

The way the fiber is spun creates different structures to the yarn.

A single ply yarn, a yarn spun out of one strand, will look softer and have less stitch definition than a tighter spun multi-ply yarn.

Want to read more about yarn structures? Check this post out!

Yarn standards

There are a few different yarn standards

  • Standard yarn weights from the yarn council.
  • The knitting and crochet community Ravelry uses a system with a few more weight categories added to it.
  • Ply – the U.K., Australia and New Zeeland use a system built on the number of plies a yarn has.
  • wpi – wrap per inch – a way of determining yarn weight based on how many wraps of a yarn that fits in an inch.

Yarn standards from the Craft Yarn Council

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

The standards from the Craft Yarn Council sorts the yarns into categories depending on the thickness of the yarn, where the thinnest yarns are labeled 0 and the thickest 7.

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

This system makes it easy to substitute a yarn with another from the same category for knitters all over the world.

Many yarn manufacturers use the yarn standards from the Craft Yarn Council. You will find them on the yarn label.

But what if you have lost the label? How should you know what yarn weight that ball of yarn is then? And which needles to use?

Then you can use the wpi – Wrap Per Inch – method to decide which category your yarn fit in.

How to determine yarn weight with wpi?

Wraps per inch, wpi, are commonly used when weaving, but can also be useful for knitters! All we Yarnies have to stick together, right!

To decide on yarn weight with the wpi-method you will need two tools that every knitter will always have on hand:

  • A ruler or tape measure
  • Something to wrap your yarn around, a knitting needle or a pen for example. You could use anything that’s a uniform cylinder.

Ready? Then let’s get to it.

  • Wrap your yarn around your knitting needle, a pen or whatever you’re using for a few inches.
  • Make sure the yarn is snuggly wrapped without crossing anywhere or leaving any gaps between the strands.
  • Measure an inch, or 2,5 cm, and count how many wraps that fit in that space. To be sure measure in a couple of different places.
  • When you know the wpi, use the cheat sheet above to compare your wpi to the standards in the first column marked Yarn Weights. If it’s hard to see the numbers on your device, please click the image to open up the cheat sheet as a pdf. Then you can zoom, download or print as you wish!
  • Think of that the wpi can vary depending on how tightly you wrap the yarn. And as always, make a swatch! More about that here

Needle sizes and yarn weights

The needle sizes listed in the cheat sheet are suggested sizes.

Every knitter has their own way to knit. Some knit loosely and need a smaller size, some knit tighter and need larger needles.

And, of course, it depends on what result you’re aiming for. Knitting lace with lace yarn on the needles listed would not result in that airy lace with well-defined holes and stitch patterns. For that, you will need to go up several needle sizes.

Yarn weight and ply

Some countries use ply as a measurement for yarn weight, U.K., Australia and, New Zeeland for example.

Yarns are made of fibers. The fibers are spun together to make them stronger and smoother.

Fibers are first spun in single strands with either an S or Z-twist. Then two or several strands are spun together in the opposite direction to make the yarn. So, if the first strands are S-twists the yarn should be Z-twisted.

This process of twisting the individual strands together is called to ply yarn.

A strand of yarn on its own is called a single as ply refers to the task of twisting strands together.

2-ply yarn is created from twisting two singles, a 3-ply from three singles and so on.

Plied yarn is stronger than singles and the finished product becomes more durable.

As mentioned before some nations use ply as a standard for yarn weights. And the ply can absolutely say a lot about the yarn, and often some about the thickness.

But the ply isn’t equal to the thickness of the yarn – the ply tells how many singles are plied together in the yarn, but not how thick it is.

A 4-ply can be thinner than a 2-ply, depending on how thick the individual singles are and how tightly they are spun rather than how many singles there are.

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