Knitting Needle Sizes & Knitting Needle Size Conversion Chart

By Jodie Morgan

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When you’re a beginner, you need to learn knitting needle sizes. It’s simple to understand, and my conversion charts will help. This knowledge makes it easier to knit your project! For a comprehensive look at knitting needles, see here.

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I reviewed, fact checked and updated this post on Jan 2, 2024

Table Of Contents

How Do I Know What Size Knitting Needles To Use?

If you’re working with a pattern, this can be a lifesaver as they tell you the ones best to use. They recommend a size and the gauge. Knit a swatch first (about 4”) with your chosen yarn, wash it, and let it dry. Once it’s dry, measure it, and it will tell you when to go up or down a size in knitting needles.

  • Too big? Size down a needle
  • Too small? Do the opposite

If you’re working on your project, choose the yarn first, then the label will tell you which needles are best to use. Looking for kid knitting needles? Use 6mm (Size 10.)

Whether your needles are single pointed, double pointed, interchangeable circular, or circular knitting needles, they all use the same size chart. Sizing differs according to which part of the world your getting them from. To help with needle conversion, I’ve included the different countries sizes below.

Knitting Needle Size Conversion Chart

Based On Standards From The US Craft Council.

Metric (mm)UKUSJapan
6.510 1/214

Here is the guide in an image format for easy reference.

International Knitting Needle Size Conversion Chart including Metric, UK, US and Japan sizes
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A few essential things about the chart. There are four sizes mentioned on this chart, Metric, UK, US, and Japan.

  • Metric is measured by how many millimeters are in the diameter of the needle.
  • UK sizing is measured in numbers getting smaller, the bigger the size of the needle. These range from 16-000.
  • US sizing is measured in numbers getting bigger, the larger the size of the needle. These range from 000-50.
  • Japan sizing goes from 0-15 as the numbers get larger, but then once they’re past 15, it switches to metric sizing.

If you can’t find a direct equivalent in your sizing system on the chart, the best bet is to find the closest metric equivalent. When you’re buying them, they’re usually listed in metric and US. These are the most common sizing systems. Australia, Canada, and New Zealand use the metric sizing system.

What Sizes Are Best For Which Projects

US Size 000-1

These are the smallest ones you can find. Probably best to avoid these if you’re a beginner, get hand pain, or don’t have the patience!

These are designed for lace or projects with intricate designs, used with very fine yarn. They’re also quite challenging to get your hands on because they’re used for particular tasks.

US Size 1-3

Instantly recognizable as the most common one used for socks. Most sock yarn is specially designed for these, and once you learn to make them, well, making socks can become addictive! (This is coming from someone who, at the time of writing, is on her fifth pair of socks!)

In addition to this article of clothing, you can also knit lovely open or lacy shawls with fine strands of yarn.

US Size 3-5

Designed for use with the sport-weight yarn, or yarn weight category 2, these needles are still considered thin.

Some of the most versatile of all of these listed, you can make all sorts of things in flat knitting and in the round, from sweaters, cardigans, and clothes, to thicker socks, baby blankets, and intricate scarves.

Sometimes your hands may cramp when using these, have regular breaks and do hand exercises to prevent this from happening.

US Size 5-7

For use with DK weight yarn (not to be confused with worsted weight yarns, as they’re slightly thicker than DK.) It’s widespread across all sorts of patterns for almost anything you could think of.

US Size 7-9

By far the most common and popular size, if you’re a beginner, this is probably the size range you’ll start with, and a good needle set includes this size. You might remember this was perhaps the one you learned with! Used in conjunction with worsted weight yarn.

US Size 9-11

Chunky or bulky weight yarn is the best choice for this type of needle. (Quick tip, it’s best to use circular needles for these large projects, as the cable holds the weight and less strain on your hands.)

US Size 11-17

Designed for bulky yarn or when you want to knit up a chunky blanket, sweater, or similar winter garment, or you want something that will knit up very quickly. Excellent for cables.

Note: Once you get past this size, there stops being even numbers in US sizing. Don’t bother looking for size 16 or 14, for example, because they don’t exist!

US Size 17 and Bigger

These are seriously large! For extreme knits with jumbo yarn (the newest addition to the yarn weight categories.)

Be warned, though, they’re quite hard to manage and might feel very awkward at first, but it becomes easier with practice. Best to get plastic or light wood materials, and avoid metal. They’re less cumbersome.

FAQS About Knitting Needle Sizes

What Is 3mm Knitting Needles In US Size?

A 3mm knitting needle doesn’t directly convert to US needle size, but the closest are 15 or 14.

What Is The Biggest Knitting Needle Size?

Probably the biggest knitting needle size is US 50, or 25mm. These needle sizes are seriously huge for super chunky yarn! If you can’t tell what size your needle is, use a knitting needle gauge.

What Size Is 9mm?

9mm knitting needles are 13 In US Size, 00 in UK size, and 9mm also in Japan.

What Size Are 12mm?

12mm knitting needles are 17 in US needle size and have no direct equivalent in the UK or Japan size.

What Size Is Us 10.5 In UK?

US 10.5 in UK needle size is 3.

What Size Is A 3.75 Knitting Needle?

A 3.75mm knitting needle is 10 in the UK, 3 in US needle size, and 4 in Japan.


Keep this post bookmarked whenever you need a handy reference, or feel free to download the image to keep whenever you need it, even when you’re offline.

I hope this is helpful for you, and feel free to share this with friends who may benefit from this resource.

About The Author

Jodie Morgan From Knit Like Granny

Jodie Morgan (Author & Founder) | Lives In: Regional Australia

Author: Jodie Morgan is a passionate knitter and blogger with 40+ years of experience currently living in regional Australia. Taught by her mother and wonderful grandmother “Mama”, she fell in love with crafting from a young age. When she’s not knitting, you’ll find her enjoying a cup of coffee with cream, or sharing helpful resources and tips with the online knitting community. Get to know Jodie and the team on our meet the team page.

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Frustrated Teacher Quits In Disgust, Sells The Farm, Moves The Family Halfway Across The World And… Starts Knitting

See what I did next...


    • Hi Jean. From my understanding a 3/4 inch diameter is 19mm and in my research I was unable to find a corresponding UK size for a 19mm knitting needle.

      If I do find out that there is a UK size I will be sure to let you know.




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