What are yarn weights and which yarn should I use?

So you're ready to start crocheting, but what sort of yarn should you use? Find out about the different weights and fibres!


So you’ve learnt your first few stitches and are officially ‘hooked’. Now it’s time to immerse yourself into the wonderful world of yarn, and there’s so much to choose from. Here’s some handy information and guides to ensure you pick the right yarn for your project!


Firstly, it’s called yarn, not wool!!!

Well, unless it is actually made of wool of course! Yarn is the general cover-all term for anything that is ‘spun thread used for knitting, weaving, or sewing’ … and crochet too! Wool, however, is yarn made specifically from sheep, goats or similar animals. It’s not a big deal, but describing something synthetic as wool to an aficionado will get you some funny looks!


What do you mean by yarn weight?

When people say ‘yarn weight’ they’re not talking about how heavy it is, they’re talking about how thick the strand of yarn is! The names can be a bit misleading (for example, 4ply is a yarn weight, but a yarn can be made from 4 strands of thread spun together and NOT be a 4ply weight yarn), and the terms used in the UK and US are different, but don’t worry, here’s our handy guide!


 UK Lace/Crochet thread | US  Fingering/10 count crochet thread

Perfect for lace shawls and delicate projects, but can be a bit tricky. Usually worked with a 2-3mm hook.


UK 4ply | US Fingering/sport

A favourite weight for baby clothes, motifs and lightweight jumpers or cardigans.


UK Double Knitting (DK) | US Light Worsted

So called because it’s usually double the weight of 4ply, DK is the most popular yarn. It’s quick to knit and crochet with and is very versatile. Usually worked with 3.5mm – 4.5mm hook.


UK Aran | US Fisherman/Worsted

Originally created for fishermen’s jumpers, aran-weight wool can be used to make many accessories and garments when DK isn’t heavy enough, and chunky is too bulky. Perfect for outdoor or warm clothing.


UK Chunky | US Bulky

Heavier than aran, chunky wool is great for outdoor wear and winter jumpers. It’s ideal for beginners because the knitted or crocheted fabric will grow quickly! Usually worked with 6.5mm – 9mm hooks


UK Super Chunky | US Super-Bulky

This weight of yarn is popular for making winter coats and jumpers. It’s also good for beginners because it produces quick results. Good for furnishings.


UK Big | US Jumbo

Quick and easy to knit and crochet with, big yarns are ideal for winter and making bold statements. You’ll need big needles or a big hook for this yarn – up to 20mm thick. Perfect for bold scarves and coats, as well as cosy cushions and throws. Can be used with hooks from around 15mm and larger!!!

A few things to remember when choosing a yarn.

Yarn weights are a great guide for choosing a suitable yarn if you’re using something different than what is recommended in the pattern, but there are some things to be aware of. You should always start by checking your tension with the yarn you’re using! This is really important because even if, for example, two different yarns say they are DK weight, there can be subtle differences between the weight of the two. The dying process (and even the colour, certain dyes can affect the final weight), the fibre content, the construction and the type of twist in the yarn can all make slight differences to weights.


If you’re taking on a large project and need a lot of one particular type of yarn, you should pay attention to the dye lot numbers. You will normally find this on the ball band (another name for the label that is normally wrapped around yarn). Because of the nature of dyes (especially so with hand-dyed yarn), one batch of yarn can be ever so slightly different in colour to another. The difference might be subtle enough that you wouldn’t notice it on the shelves in your local yarn store, but once you start making it can be really visible when you change from one ball to another.

What type of yarn should I use?

There’s so much wonderful yarn out there that sometimes it can be hard to choose. The fibre content is perhaps the most important factor to consider when starting a project – do you want it to last a really long time, do you want it to be super-soft, do you want it to be eco-conscious, do you want it to be vegan friendly – the fibres make a difference to all these factors and more! We’ll take a quick look at some of the main fibre types.


Acrylic – After a bit of a bad rep in the fibre world and being considered as ‘cheap yarn’, acrylic yarns have come on a long way since the bad old days. Many acrylics now are surprisingly soft, come in incredibly bright colours (which can be difficult to reproduce with natural fibres/dyes), and are often very even and consistent throughout the ball. It’s not as breathable or as absorbent as wool, but it’s super-strong and machine washable! The sustainability of acrylics is a factor that divides many knitters and crocheters – after all it is essentially plastic – however some people see this as being a positive as it lasts longer and isn’t susceptible to moths or wearing down – the debate goes on!


Blends – Blends are among the most popular yarns. Mills mix different fibres to create yarns that combine the best of both worlds. Want a summer yarn that feels light and breezy? Try cotton with lightweight acrylic. Love alpaca but it’s just too hot? An alpaca/wool or cotton mix will be perfect! Blends also enable mills to create unusual yarns; synthetic fibres are often used to bind ‘feature’ items like sequins to the main strand of yarn. Synthetic fibres can be much cheaper than animal or plant fibres, too. If you adore cashmere, silk or wool, keep your eyes peeled for blended yarns that feature some of your favourite fibre. It’ll usually be mixed with acrylic, viscose or nylon, and will often be cheaper, giving you more for your pennies!


Cotton – If you’re after a yarn that’s going to hold up to a lot of wear and tear, or something that you don’t want to stretch too much, then cottons are a great choice for you. They feel very smooth to crochet with, and some cottons are mercerised (a chemical process to make them even smoother and take on dye better, as well as many other positive factors). Because of their sturdiness your stitch definition (how clear your stitches look) will be very clear, which can look great but not work brilliantly overall for certain projects like certain garments as it can stretch and be a bit on the heavy side. Cotton’s are often reasonably priced and come in a wide range of colours. They’re great for summer projects, and are are a great choice for knitters and crocheters that are allergic to animal fibres.


Linen – Spun from flax from plants, linen is one of the first fibres ever to be spun. You can kind of think of it as a lightweight cousin to cotton – very strong but not a lot of stretch, definitely in the featherweight category. It’s highly absorbent which means that it works equally well in hot and cold weather, and due to it’s light weight it’s fantastic for shawls and garments (or anything that you want to drape well)


Wool – Wool is breathable yet highly absorbent, so if you get caught in a rain shower in a woollen jumper it will keep you dry. As long as it’s not a boiling hot day, it will also keep you cooler for the same reasons. Wool is long-lasting and softens with wear, so keep the moths away and a wool jumper could last decades. Thanks to its naturally anti-bacterial properties, wool also requires far less washing than other fibres. Use superwash yarn to wash it in a machine though, as otherwise it can felt! Like other animal fibres, wool has a ‘memory’. If you wet it and stretch it out (blocking) it will keep the shape it dries into, making it perfect for lace, which needs ‘opening out’ after knitting or crocheting. Choose wool for blankets, aran sweaters and close-fitting tops. If you’re worried about it being itchy, wear a short length tied around a necklace or watch and see if it irritates you.


And the rest… – there’s so many more different types of yarn that we could go on all day about it, alpaca, mohair, cashmere, silk, the list goes on! Ultimately, we can’t tell you which yarn is best, it’s down to you!