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…
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.
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 🙂
That’s so much for this article!
I reeeally want to try the “Pinterest perfect” arm knitted blankets, but they call for jumbo yarn. I have taken on board your comments about roving, but am finding it hard to source any more durable jumbo yarn in the Uk. Can you point me in the right direction? Tia!!
I’m glad you found this useful. To be honest, I’ve never come across and used a jumbo yarn that I would substitute with. I know there are some ‘filled yarns’ that I’ve seen (mostly US brands I think) that could work and be more robust but I’ve never used any of them so wouldn’t be able to comment on how they are used. The robing is great if you don’t touch it much, but not the most practical!!!
I’m just getting into this and not sure what the proper lingo is but I want to knit/ crochet a “physically heavy” blanket, and I’m trying to figure out what the best material to use is. I have been searching trying to find the heaviest weight (gram/metre) for yarn but keep getting caught up in the thickness weight. I’m thinking probably wool has the most weight compared to other materials of the same thickness classification, but I can’t find anywhere that confirms this. I want to make a blanket like my grandma made, but her memory isn’t good anymore to ask her. It was an older blanket which leads me to think it was quite possibly wool as opposed to newer threads.
This is a really interesting question. I can’t offer you a definitive answer, but my intuition says cotton or wool. It’s not just about the fibre here though, it’s also about the stitch selection / density and the yarn weight (thickness wise). I don’t really knit so I can’t answer for that, but if I were to crochet a heavy blanket (and cost of yarn wasn’t a factor) I would probably use and aran or chunky wool (or maybe cotton, depending on what it is to be used for) and work a dense crochet stitch. I hope that helps! Dora
Brilliant thank you
But can 3 strands of 4ply = Aran weight?
Erm, maybe??? Swatch and see! 😉
Can you explain to me what 8x100g means as far as yarn thickness is concerned? I have never fully understood and I’m trying really hard.
This is not a yarn thickness. This means eight 100g balls of yarn – so 800g in total. This could describe any yarn thickness. Yarn weight categories do not describe their mass (i.e. how much they weight on the scales), but relates to the thickness of the strand. The terminology can be misleading until you get used to it! I hope that helps.
Recently returned to knitting after a significant gap (30yrs, I know, I don’t look old enough) and wanting to knit a blanket for my grown up daughter, whether she wants it or not, in super chunky. Can’t find that weight in British wool so stumbled on this post in the search for guidance on combining yarns …….. WPI, what a deal breaker!! Amusing and helpful, thanks Dora
am l the only one that is more confused than l was before
Hi, what is it specifically that you’re confused about? I would love to help clarify.
I think one of the main take aways from this post is that yarn weight categories are only ever a guide given the variety of fibres and manufacturing methods. This means the maker benefits from developing their own intuition about which yarns they want to work with doe specific projects. It’s all part of the fun of the journey!
Oh,thank you so much, I realy need this information 🙂
you’re welcome. I’m glad you found it helpful.
omg i have been knitting for more than 40 years and that is the best explanation I have
ever heard. I am sure you have helped a ton of knitters to continue this wonderful craft. thanks
Thank you for the lovely comment. I’m so glad you found it helpful. 😊
Replying to your reply about my question yesterday lol:
Makes it hard when you are making a project using different colored yarns and they aren’t the same thickness 🙁
Yes – this is usually only minor but it can be an issue. It’s worth comparing the yarns before you start to understand if it is likely to be an issue. Most things can be mitigated with a bit of prep and forethought. 🙂
I read this article and all the questions & answers. I understand the labeling as far as light vs medium vs bulky etc… But what I don’t understand is how I can have 2 balls of yarn that both say medium 4 weight and yet one is half the thickness as the other? Did I miss something?
I would say that that’s mostly to do with the fibre and the way the yarn is made. Although mass produced yarns are generally consistent, even something like dye colour can impact the thickness of the yarn. It’s best to just accept it’s not an exact science – it’s an art! It’s also why I like the WPI measurement and why swatching matters!
Your posts are always very informative. Even I think that it would be more useful to include yarn WPI in the pattern instead of only yarn weight. I had posted this in one FB group too. But no one really didn’t get my point. If WPI is mentioned in the lattern, then it would be easier to substitute the yarn. Because different yarn, even in the same category have different thickness. And about holding 2 strands together, I believe lion brand chart is more accurate.
Yes, I agree. The challenge with this is that most ball bands don’t hold the WPI info. My friend Fay (provenance craft co) has just written a great blog post all about stranding after lots of experimenting. I will drop a link in the post as soon as I get a mo!
That was an interesting read, thank you so much for putting that together! ❤️ I came here looking for explanations for how two yarns, both 110 m/50 g , on the same size needles of course, knit up to very different gauges. Even this measurement, as scientific as it is, isn’t fail safe. I guess one of them fluffs up more than the other. It is my preferred categorisation though.
I’m glad you found it interesting. The meters per gram is a useful measurement for comparing yarns for sure, however, it doesn’t include fibre as a variable, the density and weight of which can make a huge difference. It’s much easier to compare yarns of a similar fibre and construction (ply, twist vs roving etc) but even then, one’s tension can be different from one day or even hour to the next – so it’s definitely an imprecise science and a glorious art! 🙂
Thank you for the info on yarn weights, it has really educated me a lot.
you’re welcome. I’m so glad you found it helpful!
can you show me (us) the z and s twists? I don’t understand how to z or s twist. thank you
So the yarn is twisted as it is spun, rather than anything a crocheter does. There’s a link to another post with more detail which may have pictures of S vs Z twist yarn which may show some examples, but when I get the chance, I will have a look in my stash and see if I can get some close ups of the different twists.
Despite crocheting and knitting for decades, I’ve found I can still learn more and certainly did here – thank you for explaining things so well! Mandatory reading for newbies and oldies! 💜
Thank you so much. This is the most wonderful feedback! I’m so glad you found the post helpful!
Thank you so much for your article. I have been reading so much about yarn and yarn choices this really helps. Yarn is not cheap and ordering via the mail is hard since you can not feel the yarn. How yarn is spun is so interesting but I have not wish to spin yarn it sounds like way to much work.
It is definitely more of a risk ordering on line if you’re not familiar with it. Usually you are able to return it if it’s not what you thought. It’s helpful to understand the spin as this impacts how the yarn crocheters up.
How did I miss this gem of an article? You answered lots of my questions and then your readers posed the questions I intended to ask. Michelle, thank you for your continuing education.
I’m so glad you found it helpful! And that the comments covered your extra questions. I always think that if I have a question, someone else will have the same one somewhere!
Thank you for making the oddities of yarn so clear. I hate swatching ( basically lazy) but didn’t really understand wraps but now I do – it makes sense. I have some Patons Fiona which I have wrapped and it’s turned out DK but it’s definitely thinner than other DK (so has more wraps) so this is a good way of comparing. I love your articles – they are clear and interesting and not a bit condescending so thank you!
I’m so glad you found it useful! Love the wraps per inch method. The one thing yo be a bit careful about is if the yarn has a halo (fluff) not to squash that together but to let the yarn kinda breathe! Thanks for the lovely feedback too!
Thanks for this, it absolutely answered my question about doubling up yarn, too. I do have an additional question on WPI, which is something I’ve wanted to know for so long but never found a definitive answer: what size (needle, hook, pencil- whatever you use!) do you wrap the yarn around? I’m thinking that you’ll get more wraps around a 3mm hook/needle than you would around a 10mm hook/needle. So what’s the consensus on this? What size do you use? Thanks, Jen
I’m glad you found this helpful. The size of the item you wrap shouldn’t matter as you’re measuring the width of the yarn rather than the length – if that makes sense. So if you wrap it wound a pencil, the width of the wraps would be the same as if you wrapped it round a rolling pin (for example), but for the latter you will use a much longer length of yarn. I. Hope that makes sense!
Your article exactly answered the question I asked Google — do two strands of lace weight equal dk. I found some gorgeous lace weight in a colour my daughter wants for a hat, but the pattern will probably call for dk or a light aran. Problem now solved. Thank you!
I’m so glad you found this useful! I hope your daughter likes her hat!
Thankyou sooooo much for your post on yarn, ever since I started crocheting 2 years ago I have never understood yarn weights. I have stuck to dk and any 100% cotton for kitchen bits. Now I feel a bit more confident in finding a fingering weight yarn to do a beautiful shawl I bought the pattern for. You should put all these posts of crochet knowledge into a book for us to purchase (remember some of us have tight budgets lol) I see it being on every crocheters bookshelf especially mine There is such a need for something like this in the market, the way you have written this article. I have read many but yours has made sense so thankyou and please email when you have written xxxx
Ahh. Thank you so much for that feedback. I’m so glad I could help you out! Most of my posts are inspired by things that confused me when I started (and some things that still do), so I get where you’re coming from!!
(And the book is on the to-do list, an ebook at least!)
Hi, l love your article.
Question, what is the meaning of PA?
I would like to understand the comparison.
Sorry – bad form not explaining my acronyms! PA is personal assistant! (VA = virtual assistant)
I’m glad you fount the article useful! 😊
I wish I had thousands of followers so that I could instruct them all the follow you: you are a bloody FOUNT OF WISDOM for those learning to crochet and also those who’ve been doing it for a while but haven’t yet ventured into challenging themselves ..
I hope you’ll issue some kind of assemblage of all this, Michelle ! – if you ever finish .. [grin]
Ahh. Thank you! I’d love to put it all together one day (I have the chapters outlined and everything!) but other things always seem to demand my time!!!
And thank you for your continual boosting of my ego! 😊
Shouldn’t need boosting, mate.