Yarn weights explained

Working with different yarn weights in crochet is one of those pesky areas which can be really confusing. Especially when you’re new to the craft.

It’s even more important to understand the yarn weight system when you’re trying to follow a pattern which you want to fit a body or work up to a specific size.

So today I want to take some time to explain it from the top, addressing some of the common myths and clearing up some grey areas.

This is your ‘all the things you ever wanted to know about yarn weight but were afraid to ask’ post…

In the simplest terms, yarn weight refers to the thickness of the yarn.

With the different types of yarn available in different parts of the world, I often get asked whether my crochet garment patterns can be made either in a different yarn of the same weight, or different yarn weight to the one used in the pattern.

To the first question I answer “probably”, to the latter, “it depends”.

The truth is that nothing is completely straightforward when it comes to yarn weights, but understanding the system helps you answer the questions for yourself.

It was actually the inconsistencies in tension across the same yarn weight categories that inspired me to create the Any Yarn Will Do sweater pattern and later it’s crochet cardigan pattern cousin!

I talk a little more about substituting yarns in this post about choosing the right yarn for your project, but to do that, you need to understand what yarn weight actually means to begin with.

What is yarn weight?

In the simplest terms, yarn weight refers to the thickness of the yarn.

The ‘heavier’ a yarn is, the thicker it gets. The lighter yarns are finer or thinner.

It has nothing to do with how much your yarn weighs when placed on a scale.

In the image below, you will see 6 different yarns which represent the most common yarn weights used for crochet. From bottom left, up and clockwise, and from heaviest to lightest, these are: Super Chunky, Chunky, Aran, Double Knit, 4 ply and Lace Weight.

When laid out together like this, it’s easy to see the variation in thickness.

Keep reading for a full table of yarn weight categories and information about how all the different terms for weight classes compare.

So now you have a fundamental idea of what yarn weight is, let’s look at why it’s important.

Why does yarn weight matter?

Measuring yarn weight is important for standardisation.

It helps yarn producers with consistency, helps designers communicate what yarn to use and helps makers pick the right yarn in their local yarn store or online shop.

If we’re not all hooking from the same hymn sheet, then following a pattern and being able to recreate a designer‘s work, or your own projects for that matter, will be impossible.

Below is an example of two projects I made before I understood gauge and yarn weights.

I made the black hat in a yarn weight which was much too heavy so it’s huge. The blue hat is (more or less) the correct size, the cat is laughing at me without mercy!

I often wheel this picture out when I’m talking about measuring gauge, but the issue here was actually made worse because I used a different yarn weight to that given in the pattern.

You can see that I tried to make it better on the black hat by making a smaller brim. It did not work…

I hope I’ve made the point!

How is yarn measured?

There are two main ways of measuring the ‘weight’ of yarn.

The one you will likely be most familiar with is the yarn weight categories, such as double knit or worsted, or a number, which you’ll see marked on most ball bands.

Another, more traditional, measurement is wraps per inch.

Whichever method you use, there is always going to be some variation within a specific weight class.

Yarn weights are on a spectrum, a continual scale of thin to thick. They don’t all sit neatly in the centre of an arbitrary category.

Fibre arts are not an exact science (probably why they are called arts!!!) and this is a facet of the craft. It’s something to be embraced and incorporated. It’s also a reason to make the gauge swatch if you want something to fit!!

Let’s take a look at these two measurement options in a bit more detail.

Measuring yarn in wraps per inch

Confession time.

Until I started digging deep into research mode for this post, I had never heard of this measurement method before. Honestly, I think it’s more a knitters thing, but once I learned it, I realised it’s kind of cool!

If you don’t have a ball band to refer to, or the weight is not given on it, this method can be a great way to check your yarn weight, and to compare two different yarns.

The measurement given is just the number of times you can wrap your yarn around something (a knitting needle, pencil or aluminium crochet hook for example) over the length of one inch. Hence the literal name wraps per inch.

If you keep scrolling to the chart below, You’ll see how the wraps per inch. measurement compares with the rest of the more familiar yarn weights.

The picture below demonstrates how it works using a Tunisian crochet hook as my wrapping tool of choice.

In this measurement, the strands of yarn should be laid flat next to each other, just touching but not squishing together.

I’ve used an old scrap of aran yarn in the image above and have 10 wraps in one inch (if my eyes didn’t cross and get it wrong).

Check out the yarn weight table below to see if the system works!

If this is always measured manually you can see why you’re going to get some inconsistencies!

This is one of the reasons wraps per inch (or WPI) are often given in bands. So for example, 11-15 wpi would be equivalent to a double knit yarn.

Yarn weight categories

Yarn weight category or class is the type of measurement I imagine you’re all more familiar with. It’s certainly the one I use the most.

The chart below outlines the most common weight categories and the different names for them, including the approximate wrap per inch count (wpi).

With thanks to The Craft Yarn Council of America for use of their symbols

That pink scrap of yarn I wrapped earlier was an aran weight yarn (left over from the everyday hugs cardi). Its 10 WPI measurement was bang in the centre of the Weight 4 worsted/aran weight category. I love it when a plan comes together!

Depending on which country you’re based in, some of the categories may be more familiar than others.

Because I’m UK based, the number system, which isn’t commonly used here, means very little to me in an intuitive sense, but if you’re used to shopping for yarn in the US then the category numbers probably make much more sense.

I learned to crochet using dk and aran yarn and you rarely see these numbers on a UK Yarn brand ball band (try saying that really fast 3 times!!).

This is not a perfect system and there is so much overlap just within one weight category. This makes exact comparisons difficult just by using the name of the weight class.

For example, Aran and Worsted are in the same category. They are often used interchangably as options in patterns (including by me) but actually, the variation can be huge.

That hat disaster I mentioned above. That was me using an aran weight yarn with a pattern that called for worsted weight.

This is why gauge also matters so much as well as yarn weight.

Now you understand the different measures of weight, I want to dive into what it is that gives a yarn its thickness.

To understand this, we need to take a step back and think about the processed involved in making yarn.

How is yarn made?

Traditional, yarn is made by twisting (spinning) fibres (or a blend of fibres) into a thread.

Each strand of this thread is known as a ‘single’ or ‘single ply’. These singles can be smooth or ‘fuzzy’, will vary in thickness depending on the type of fibre(s) used and the process by which they are created. (See woolly vs worsted below.)

Multiple single plies are twisted together to make a thicker strand of yarn, which is what you will crochet with.

The way in which the singles are twisted (Z or S twists) and the number of singles twisted together will determine the weight of the resulting yarn.

For example, twisting 8 plies together will create a 8 ply yarn.

Two factors impact yarn weight; the weight of the single plies and the number of plies twisted together.

I hope that provides a useful initial overview of the yarn weight system, but I know you will have many additional or follow up questions.

I have listed some of the FAQs below which elaborate on the topics above. This is for those of you who like the detail and to know ‘why.’

Yarn weights: Frequently asked questions

To address some areas of confusion surrounding the terminology and myths which come up over and again, I’ve created an FAQ format.

If you have a yarn weight related question I haven’t addressed then drop it in the comments and I’ll do my best to answer it.

Are all yarns in the same weight category the same weight?

Are all double knit yarns the same? Is a sock yarn the same as 4 ply?

In short no.

I touched on this earlier but there is huge variation within individual weight categories. It’s impacted by many factors such as fibre and manufacturing process.

You may even find variations in weight between different colours of the same yarn because of the dyeing process.

Never just substitute a yarn based on weight category alone. Wraps per inch is an additional way to compare yarn weights, but if you want it to fit, make a swatch and check your tension.

What is worsted yarn?

This is an important one. Worsted weight yarn is not the same as worsted yarn.

‘Worsted weight yarn’ is a weight category.

‘Worsted yarn’ is a term used to describe the way a yarn is spun. The difference is important.

Woolen and worsted yarns

Woolen and worsted are two different ways that yarns are spun.

Here’s a simplistic overview of the difference, and why it matters.

In woolen spun yarn, the fibres are ‘carded’ before they are spun into threads and air is introduced. With worsted yarn, the fibres are ‘combed’, smoothing them out and creating a smooth denser yarn.

Think about back-combing your hair versus using a hair straightener on it.

The differently spun yarns will often behave in different ways.

The smooth worsted yarns tend to give more drape, durability and water resistance (the smooth fibres don’t let the water in).

Woolen spun yarns are more elastic, light, fluffy and warmer, because of all that trapped air for insulation. Woolen spun yarns will tend to have less stitch definition as the ‘bloom’ or ‘loft’ of the yarn ‘fills in the gaps’.

Those people who find wool ‘itchy’ on the skin may well be wearing woolen spun yarn. The fibres on woolen spun yarn tend to stick out at different angles creating a fuzzy halo which can irritate.

If that’s you, and you don’t have an allergy to the fibre, you might find items made from worsted spun a little more comfortable.

Are Aran and Worsted Weight yarns the same?

As illustrated with my hat debacle, no they are not.

These terms are both in the medium weight category and often used interchangeably, by myself included.

Generally speaking, but not always, aran weight yarns are heavier than worsted wight yarns. So… make a tension swatch… have I hammered that message home enough yet?

I have noticed that worsted weight yarns tend to be more common with US yarn brands where as European brands tend to offer more ranges in aran. I guess it’s some historical legacy thing?

That doesn’t necessarily mean that you can’t use an aran weight in a pattern calling for worsted. You just need to make sure that you get gauge, and get it with a drape that will work for the pattern.

Although I believe that gauge is the deciding factor, it comes with a caveat. You could probably match gauge with a chunky yarn for a worsted weight yarn pattern if you used a small enough hook, but you probably wouldn’t want to make a cardi out of the resulting fabric because it would be super dense and not very flexible.

Your swatch will give you an idea of the density and drape of the fabric and help you decide if the yarn is suitable for your project.

Gauge may be boss, but drape is their PA, the one that oils the wheels and actually makes things happen.

Anyone who has has been or had a good PA knows that the boss is nothing without one! (Disclaimer, I was a corporate PA for 12 years and then a VA for a while. They are priceless!)

Back on topic Dora!

Similarly with the aran / worsted comparisons, 4 ply, fingering weight and sock yarn are often bunched together but there will be some variations between them.

Furthermore, I find that some 4 ply yarns are closer to the thickness of what I expect a typical double knit to look like. It is all one big spectrum.

The more I think about the WPI measurement, the more I realise how useful it is in a practical sense!

Can you double up yarn to make a heavier yarn weight category?

In crochet, you will sometimes see people work projects double stranded. That is, crocheting with two strands of yarn held together to create a thicker yarn.

Because of this, I often hear people asking if using two strands of double knit is the equivalent as using aran, or of using two stands of aran or worsted is the same as chunky, and so on.

I spent a while googling this and there are many suggestions of pairing yarns together to make different weights. I’ll add some of these below, but my thoughts are that it’s not an exact science. So I’ll say it again… make a tension swatch if you want it to fit!

The list below seems to be the consensus for doubling up yarn weights;

• 2 strands lace weight = 1 strand fingering
• 2 strands sock weight = 1 strand double knit
• 2 strands fingering weight = 1 strand worsted
• 2 strands double knit = 1 strand aran
• 2 strands worsted weight = 1 strand chunky
• 2 strands chunky = 1 strand super chunky

This is what the Lion Brand Website advises:

• 2 strands fingering weight = one strand sportweight
• 2 strands sport = one strand worsted weight
• 2 strands worsted = one strand chunky to super bulky weight

(That last one from Lion Brand is unhelpfully vague but also illustrates the point I’m making)

If you want to get scientific about this, you can use the gauge measurements on the ball band and do the maths. That said, it won’t account for the gaps between the two yarns so you’ll need to add a bit for that. No matter how tight you hold them together, you won’t match a spinning machine!

Is 8 ply twice as thick as 4 ply?

Following on from the last question, maybe using plies is a more accurate way of working out if yarns can be doubled up?

Not really because not all plies are equal. The thickness comes from the thickness of each ply, not just the number of them.

Categroies such as 4ply are often using it as a common term rather than a literal one. And in this circumstance a 4 ply weight yarn does not necessarily have to have 4 strands.

Clear as mud!

What is Roving?

You will often see roving associated with super bulky jumbo yarns. But that’s only a small part of the story.

Roving is, if we’re being pedantic, not actually yarn. It is the carded fibre, that is used to spin into yarn. But it’s bundled together to come a simple loose cable like thread, rather than spun into plies.

Roving is what is used to spin the woollen type of yarn we used earlier. It is great for felting projects and looks beautiful in weavings and wall hangings.

I’m sure you will have seen roving used to make those giant hand knit blankets on Pinterest or instagram. It is soft, beautiful to look at and totally stroke-able. But the cold hard truth is that true roving is not very practical when used as yarn. Those beautiful blankets look so pretty but try to actually use them and they pill and fluff like nobody’s business, I’ve tried it and it’s not pretty! Sorry to crack that perfection veneer. The good news is that there are other jumbo yarns available which are a bit more durable!

Note that the equivalent fibre that is combed to make the worsted type of yarn is called ‘top’.

Can I use meterage or yardage per ball to compare yarn weights?

This is an interesting one, obviously the answer is ‘it depends.’

If you’re comparing yarns made with a similar spin using a similar fibre content, then comparing the meterage of yarn in equal weight balls can give you a good indication of whether they might be a good substitute.

I find this useful when looking at bulky and super bulky yarns as there is so much difference in that category. An extra 20metres in a 100g ball of super chunky is a lot more of a difference than a difference of 20metres in a 100g ball of lace weight.

You do need to be careful about the fibre content here. A fibre like cotton is quite heavy compared to the same volume of something like mohair.

For example, you might get the same meterage of yarn in 20g of fine mohair than you would in 100g of fingering weight cotton.

So it’s a useful tool, but one to be used with caution.

Are Aran sweaters made of aran yarn?

In a word; not necessarily, but they can be. That’s 6 words but I’m allowing for artistic license.

Aran sweaters are typically wool (the fibre) cabled sweater designs, sometimes referred to as fisherman sweaters. Their name comes from the Aran Islands, just off the coast of Ireland. Not the type of yarn used.

Aran sweaters are traditionally knitted, but my ‘It’s just not cricket’ sweater is a tribute to the traditional cable knit sweater. It was inspired by an Aran sweater though.

And on that note, I think I’m yarn weighted out!

If there’s anything you think I’ve missed about yarn weights then please do let me know in the comments. This is something I’m still learning about too.

I hope you’ve found this useful and that it will inform you yarn choice for your next project a little more!

But for now, happy hooking

Dx

P.S. In case you were wondering, dk is my favourite 🙂