One of the most common knitting problems that you can face is using the wrong size of needle. By using this quick reference guide, we can help you ensure that your knitting needle size matches your yarn. So you can get off to the perfect start with your next knitting and crochet project!
Before starting any project, it's essential that you know the weight of the yarn you plan to use. When we talk about yarn weight, we're referring to its thickness. If you're making socks, you'll most likely want to use a fine yarn - but if your project is a cosy blanket or a thick jumper, you'll want something a lot thicker!
The weight of your yarn is the most important factor when it comes to choosing the right size knitting needle or crochet hook. In general, a basic rule of thumb is: the finer the yarn, the smaller the needle.
Most patterns will specify the yarn that they used to make the project. If you didn't want to use the exact same yarn, you could substitute for something which is the same weight yarn.
Knitting needle and crochet hook sizes
It's easy to get confused with terminology when you see needles and hooks discussed online. That's because there are three different numbering systems that people use to talk about sizes!
In the UK and most of the world, it's common to use the metric system to talk about needle sizes. The smallest widely available needles are 2mm, while at the top end of the spectrum, it's possible to find very large needles of 10mm or more.
Americans use their own numbering system, which you will often see if you're using patterns from the USA. In this system, 2mm needles are a size 0, and the numbers go up as the needles get bigger. Confusingly, there's also an old British system where the numbers go down as the needles get bigger, so 2mm needles are a 14. This isn't used very much anymore, but you may still see it on vintage patterns.
Crochet hook sizes in the UK use the metric system, but they may also be referred to by a letter or a number. Japanese patterns, which are very popular in the crochet world, use their own numbering system! Luckily most patterns will include a metric conversion. So this makes things a bit easier to follow if you are looking for crochet hook sizes in the UK style.
Knitting needle sizes for yarn
This table provides a general suggested guide for knitting needle sizes and crochet hook sizes and yarn. Be sure to check both your yarn weight and your needle size carefully before starting any projects.
Metric Needle Size
US Needle Size
Metric Hook Size
US Hook Size
Yarn Weight2 - 3 ply
Yarn NamesLaceweight, light fingering, superfine
Metric Needle Size2.25 - 3.25mm
US Needle Size0 - 2
Metric Hook Size1.5 - 2.25mm
US Hook SizeB
Yarn Weight4 ply
Yarn NamesSock, fingering, baby, fine
Metric Needle Size2.5 - 3.5mm
US Needle Size1 - 3
Metric Hook Size2.25 - 3.5mm
US Hook SizeC - D
Yarn Weight5 ply
Yarn NamesSport, baby
Metric Needle Size2.75 - 4mm
US Needle Size2 - 4
Metric Hook Size3.5 - 4.5mm
US Hook SizeD - G
Yarn Weight8 ply
Yarn NamesDK, double knit
Metric Needle Size3.75 - 4.5mm
US Needle Size3 - 6
Metric Hook Size4.5 - 5.5mm
US Hook SizeG - I
Yarn Weight10 ply
Yarn NamesWorsted, aran
Metric Needle Size4.5 - 5.5mm
US Needle Size6 - 8
Metric Hook Size5.5 - 6.5mm
US Hook SizeI - K
Yarn Weight12 ply
Yarn NamesChunky, bulky
Metric Needle Size5.5 - 8mm
US Needle Size8 - 11
Metric Hook Size6.5 - 9mm
US Hook SizeK - N
Yarn Weight14 ply
Yarn NamesSuper chunky, super bulky
Metric Needle Size8 - 12.75mm
US Needle Size11 - 17
Metric Hook Size9 - 15mm
US Hook SizeN - Q
When to go up or down a needle size
Matching knitting needle or crochet hook sizes and yarn can sometimes be a bit more complicated. You should also think about the nature of the project. Sometimes it's a good idea to use a bigger or a smaller needle, depending on the effect that you want to achieve.
Using the needle sizes in our table will generally give you a knitted fabric that is neither very tight nor very loose. It will not have visible gaps between the stitches, but the finished fabric will not be particularly rigid, either.
Choose to use larger needles if you'd like an airy fabric with visible holes between the stitches. For example, you could make a loose, drapey jumper by using finer yarn with bigger needles. The finish result would be somewhat see-through, and would have a relaxed feel to it.
Smaller needles are great if you want a piece that's going to be a bit stiffer; for instance, if you are crocheting a basket or hat, you might want a tight, rigid fabric. Smaller needles can also be a good idea for certain knitting designs, such as Fair Isle colourwork or cables.
It's not generally a good idea to try to change the size of a pattern by sizing up or down your needles. For example, you might want to make a jumper pattern oversized, by using larger needles than the pattern suggests. However, you'll probably end up with extremely large arm holes and a bad fit - not the chic style you were going for!
What is gauge and how does it affect needle sizes?
There's one final thing to take into account when you choose needle sizes: gauge. In the knitting world, gauge refers to the number of stitches and rows per centimetre. When you follow a pattern, it should tell you what the gauge is. If your knitting matches the pattern's gauge, then your project should turn out well.
Gauge can be affected by a number of things. Different fibres might behave differently. So if you are knitting with a DK yarn made of cotton and the pattern is written for a DK yarn made of wool, your gauge could be off. Also, every knitter is different. Some of us naturally knit more tightly, while others have looser stitches. There's nothing wrong with this, but it's important to be aware of it.
In some projects, gauge doesn't really matter. For example, if you're making a blanket or a scarf, you might not care if the finished result is a few centimetres bigger or smaller than the pattern indicates. However, if you're making a fitted garment, like a jumper or cardigan, getting gauge right is essential.
Before you start your project, knit a test square. Block it, as you would for a finished piece, as many yarns stretch after blocking. Then measure it and compare it to the pattern gauge. Now you may need to choose a larger or smaller needle, so your gauge matches the design.
Choosing the best needles for your project
Although knitting needle sizes are standardised, materials are not. Many of us learn to knit with straight metal or plastic needles, but there are other types you might want to try out. Here's a quick guide:
Knitting needle materials
Metal needles: these might be made from stainless steel, aluminium, or nickel. They have sharp, pointy tips which makes them ideal for knitting with fine yarns or creating intricate stitch patterns. The slippery surface is good for knitting quickly, but can be difficult with slippery yarns, like cotton. Some knitters find that metal needles can be uncomfortable during long sessions. Our most popular metal needles are the Chiaogoo Twist interchangeables.
Plastic needles: they are very lightweight, which makes them great if you need extra large needles. They're a budget-friendly option and useful for getting started. However, they can warp over time, and may not last as long as other materials.
Bamboo needles: these needles are also lightweight, and are an eco-friendly choice. They're great for slippery yarns, but you might find that fuzzier yarn, such as mohair, sticks to them a little. Take care when storing them, as they can snap! We stock some gorgeous bamboo needles from Chiaogoo and LYKKE.
Wooden needles: As with Bamboo, these are a great choice for when knitting with more slippery yarn if you find that your stitches usually slide off your usual metal needle tips. Our favourite wooden needles are from LYKKE and come in a fabulous range of colours.
Remember, knitting gauge is very sensitive. If you change mid-project from plastic to bamboo needles, for example, you might find that your gauge changes, too.
Types of knitting needles
Straight needles: these are the most common needles around. They are useful for knitting flat objects, and are a good way to get started for beginners.
Circular needles: these are needles connected by a flexible cable and can either be fixed or interchangeable. Different lengths of cable are available. Circular needles allow you to work in the round, creating a tubular piece of knitting that might become, for example, the body of a jumper. They're also handy for working on very large projects such as blankets. We stock fixed circulars and interchangeable sets, including all of the needle tips and replacement cables.
Does changing needle size really make a difference?
Yes! This is particularly true at the lower end of the needle size spectrum, when what seems like a small change in diameter can really have a big impact. You might be surprised to find that there can be such a big difference between needles of 3 mm and 3.25 mm.
How can I check my knitting needle size?
Some knitting needles are numbered with their size, but many are not. Don't panic, though. A needle gauge is a very simple, cheap piece of equipment that ever knitter should own. It is a strip of plastic or wood with holes punched into it, allowing you to quickly check what size your needles are. Many needle gauges also have markings so you can use them as a ruler, making them extra useful.
What size needles should I use for chunky wool?
A pattern using chunky wool will generally need large needles. Around 7 - 8 mm is average, while 5.5 - 6 mm will give you a tighter fabric. Super chunky wool, which is ideal for making a very thick blanket, will need even bigger needles.
What size needles should I use for DK yarn?
DK yarn is one of the most common yarn weights, often seen as the standard weight that sits halfway between fine and bulky. Needles of 3.75 - 4.5 mm will usually give you a good result with DK yarn.
What size crochet hook should I use for chunky wool?
A large crochet hook, at least 6.5 mm, should be used with chunky wool. The larger the hook, the more space you will see between stitches.
What size crochet hook should I use for DK wool?
When crocheting with DK wool, it's a good idea to use a hook of 4.5 - 5.5 mm. Size up for an airier finish, or size down for something more rigid.
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