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Knitting needle sizes and conversion chart

Find out how to measure your needles and convert between UK, US and metric sizes with our guide to knitting needle sizes.

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By Sarah Winsper

Published: December 28, 2020 at 8:55 am

Knitting needle sizes can be confusing, but don’t worry – we’re here to help you make sense of them. Countries label their knitting needles in different ways, so the number on your needle may mean a different thing depending on where in the world you live. In this article we’ll explain more about these numbers, show you how to measure knitting needle sizes, and provide a knitting needle conversion chart for UK, metric and US sizes. In our guide you’ll find:

What do knitting needle sizes mean?
How to measure knitting needle size
Knitting needle gauge: 3 to buy
Knitting needle conversion chart
Knitting needle conversion chart printable

What do knitting needle sizes mean?

The size on a knitting needle tells you its diameter. This measurement is important because the needles you choose can have a huge impact on your finished project. If you choose needles that are too big for your yarn, you’ll end up with large, loopy stitches, and if you choose needles that are too small your stitches could be tight and hard to knit. Take a look at our yarn weight conversion chart and beginner’s guide for more on which needles are best for which yarns.

The knitting needle size may be written in a number of different ways, depending on where it was made. Many needles are labelled using metric units, but the UK and US also have their own numbering systems and, confusingly, they work in opposite directions. In the UK, the scale runs from 14 (the smallest size) to 000 (the largest size), while in the US it runs from 0 (the smallest size) to 50 (the largest size). And for some common metric needle sizes there’s no UK or US equivalent at all! To get your head around all of this, you need a knitting needle conversion chart, and we have one for you below.

How to measure knitting needle size

Most new needles have the size printed somewhere on the end or side of the needle, but what about those hand-me-down or charity shop pins where the number was rubbed off years ago, if it ever existed in the first place? To determine the size of these mystery needles, you need a knitting needle gauge.

These handy tools are an essential part of any knitting starter kit, and many also offer other functions such as enabling you to measure knitting tension squares or even cut your yarn. They are made from sturdy wood, plastic or sometimes metal, and feature a collection of holes, from small to large, each with a number next to it. All you need to do is push the point of your mystery needle through each hole in turn, until you find the one where it fits perfectly. Then read off the number next to the hole and this will tell you the knitting needle size – easy!

Knitting needle gauge: 3 to buy

Pony Knitting Gauge

We love how many tools Pony have crammed into this clever needle gauge! As well as measuring needle sizes from 2-10mm it also has a ruler, and a blade for cutting yarn. There’s a separate version for measuring larger needle sizes too.

Buy it from Deramores’ UK store or US store.

Knit Pro Needle View Sizer

This little gadget measures needles from 2-12mm, and also comes with a ruler in both centimetres and inches. There’s a clear window in the ruler that enables you to measure your knitting gauge – handy when swatching for a new project.

Buy it from Amazon.

Cat Needle Gauge

A must for cat lovers, this cute gauge from Under the Olive Tree Knits measures needles from 2mm to 12mm in size. It’s made from plywood and varnished for a natural finish. Stash it in your project bag to measure needles on the go.

Buy it from Etsy.

Knitting needle conversion chart

UK needle size

Metric needle size

US needle size

2mm

2.25mm

–

2.5mm

–

2.75mm

3mm

–

3.25mm

–

3.5mm

3.75mm

4mm

4.5mm

5mm

5.5mm

6mm

6.5mm

10½

7mm

–

7.5mm

–

8mm

9mm

000

10mm

–

12mm

–

15mm

–

20mm

–

25mm

These are the most common needle sizes you’ll see, but if you’re in doubt about your needle size always check it using a needle gauge.

Knitting needle conversion chart printable

Here’s a handy version of the conversion chart for you to save and print:

More knitting tips

Take a look at our how to knit section for more knitting advice and inspiration. Find out how to choose the right knitting needles for your project and learn all about knitting tension squares to get accurate results. Plus see our knitting abbreviations for all those hard-to-remember knitting terms, and how to cast on knitting for all you need to know about this crucial technique!