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Guide to Knitting Needle Sizes (+ Conversion Chart)

When it comes to knitting, choosing the right needle size is essential. But different countries use different numbering systems, so it can be hard to know what size you need. This guide will help you make sense of all the different systems for knitting needle sizes and find the perfect size for your project.

We’ll also provide a conversion chart to make it easy to find the right size, no matter where you are in the world! Read on for everything you need to know about knitting needle sizes!

Guide to Needle Sizes

If you’re new to knitting, it can be tough to figure out what size you need for your project. But don’t worry, it’s not as complicated as it seems!

Knitting Needle Size Chart

This chart is a great starting point when you’re trying to figure out what size knitting needles to use. It compares metric measurements with the standard US and UK numbering systems.

Metric (mm)US SizeUK Size
1.0 mm00000 (5/0)19
1.25 mm0000 (4/0)18
1.5 mm00017
1.75 mm0015
2.0 mm014
2.25 mm113
2.5 mm
2.75 mm212
3.0 mm11
3.25 mm310
3.5 mm4
3.75 mm59
4.0 mm68
4.5 mm77
5.0 mm86
5.5 mm95
6.0 mm104
6.5 mm10 1/23
7.0 mm2
7.5 mm1
8.0 mm110
9.0 mm1300
10.0 mm15000
12.5 mm17
15 mm19
19 mm35
25 mm50
35 mm70
source: craftyarncouncil.com

Different Systems of Measurement

Not all countries use the same system of measurement, so it’s important to know how to convert between them. Here are some of the most common measurement systems you’ll come across:

Metric: The metric system is used in many countries. In the metric system, needle sizes are given in millimeters (mm).

US: In this system, needle sizes range from 00000 (1 mm) at the smallest to 70 (35 mm) at the largest.

UK: In the UK, needles are numbered in the opposite direction. They range from 19 (1 mm) at the smallest to 000 (10 mm) at the largest.

Japan: The Japanese system ranges from 0 at the smallest to 15 at the largest.

Japanese Knitting Needle Size Chart

Here is a knitting needle size chart that compares metric measurements with Japanese knitting needle sizes.

Metric (mm)Japanese Size
2.1 mm0
2.4 mm1
2.7 mm2
3.0 mm3
3.3 mm4
3.6 mm5
3.9 mm6
4.2 mm7
4.5 mm8
4.8 mm9
5.1 mm10
5.4 mm11
5.7 mm12
6.0 mm13
6.3 mm14
6.6 mm15

Old vs. New US Knitting Needle Size Chart

But what if you’re using a vintage knitting pattern or using vintage knitting needles?

In the past, the US used a different system to size needles. In the old US system, knitting needle sizes ran opposite of current sizing – that is, the smallest needles had large numbers, and the largest needles had small numbers.

So, if you’re looking at an old knitting pattern or using antique needles, you might notice that the needle sizes differ from what you’re used to.

Here is a chart showing the old US needle size system, sourced from Complete Guide to Modern Knitting and Crocheting by Alice Carroll, published in 1942.

Metric (mm)New US SizeOld US Size
1.0 mm5/018 (steel DPNs)
1.125 mm17 (steel DPNs)
1.25 mm4/016 (steel DPNs)
1.5 mm00015 (steel DPNs)
1.75 mm0014 (steel DPNs)
2 mm013 (steel DPNs)
0 (standard needles)
2.25 mm112 (steel DPNs)
2.5 mm1 (standard needles)
2.75 mm211 (steel DPNs)
2 (standard needles)
3 mm10 (steel DPNs)
3 (standard needles)
3.25 mm3
3.5 mm49 (steel DPNs)
4 (standard needles)
3.75 mm58 (steel DPNs)
5 (standard needles)
4.0 mm6
4.25 mm6 (standard needles)
4.5 mm7
4.75 mm7 (standard needles)
5.0 mm88 (standard needles)
5.25 mm9 (standard needles)
5.5 mm9
5.75 mm10 (standard needles)
6.0 mm10
6.5 mm10 1/210 1/2 (standard needles)

What’s the Best System to Use?

There is no “right” or “best” system of measurement – it really depends on where you are in the world. In Europe, the metric system is more common. If you’re in the United States, you’ll find needle sizes listed in both millimeters and the US system. And in the UK, you’ll find both millimeters and UK sizes.

That said, it seems more designers and yarn manufacturers are using the metric system, so it’s a good idea to familiarize yourself with it. That way, you’ll be able to easily find the needles you need no matter where you are in the world!

Why Does Needle Size Matter?

It goes without saying, but needle size is very important. The diameter of the needle will affect your knitting gauge – that is, how many stitches and rows you knit per inch of fabric.

Controlling for the same yarn, a larger needle will create fewer stitches per inch (a looser fabric), while a smaller needle will create more switches per inch (a denser fabric).

So, if you want your knitting to match a specific gauge (say, for a sweater pattern), you’ll need to use the needle size that gets you there.

women knitting with straight needles
knitting with straight needles

How Knitting Needle Sizes Work

The needle size is determined by the diameter of the needle, which is indicated in millimeters (mm). The larger the number, the larger the diameter, and vice versa.

The US needle sizes range from 0 (the smallest) to 70 (the largest). These numbers correspond to the diameter of the needle.

Needle Length vs. Needle Size

When looking for knitting needles, you’ll notice that they come in different lengths, too. Here’s how that works:

Straight Needles

Straight needles come in different lengths, typically 10 inches, 14 inches, and 16 inches. The length doesn’t affect your knitting gauge, but it does affect how many stitches you can fit on the needle.

Choose a needle length based on the project you’re working on. A good rule of thumb is that longer needles are better for wider projects like sweaters, and shorter needles are better for narrower projects like scarves.

knitting project on circular needles
knitting with circular needles

Circular Needles

Circular needles are two needle tips that are connected by a flexible cable. Circular needles are available in different lengths, too. The most common lengths are 16″ (40 cm), 24″ (60 cm), 32″ (80 cm), and 47″ (120 cm) – but each brand will have a slightly different range.

Tip: Circular needles are measured from tip to tip. The measurement includes the length of each needle tip, not just the length of the cable.

The length of the circular needle you choose will depend on the project you’re working on. And as a general rule, you want to select a circular needle that’s smaller than the circumference of your project. For example, if you’re knitting a hat with a 20″ circumference, you want to use a 16″ circular needle.

knitting project on double pointed needles
knitting with DPNs

Double Pointed Needles (DPNs)

Double-pointed needles (DPNs) are short needles that come in sets of four or five. They’re typically used on small projects like socks, mittens, and the tops of hats.

Like straight needles, the length of DPNs doesn’t affect your gauge. But, the length does determine how many stitches you can fit on the needles. DPNs come in lengths ranging from 4 inches (10 cm) to 8 inches (20 cm).

Yarns Weights and Needle Sizes

Different needle sizes are used with different thicknesses of yarn. In general, smaller needles are used for lighter yarns, and larger needles are used for thicker yarns. 

The following chart shows the seven different CYC yarn weight categories, along with their recommended knitting needle sizes in metric and standard US sizes.

Yarn WeightMetric (mm)US Size
0: Lace1.5 to 2.25 mm000 to 1
1: Superfine (fingering, sock)2.25 to 3.25 mm1 to 3
2: Fine (sport, baby)3.25 to 3.75 mm3 to 5
3: Light (DK, light worsted)3.75 to 4.5 mm5 to 7
4: Medium (worsted, aran)4.5 to 5.5 mm7 to 9
5: Bulky5.5 to 8 mm9 to 11
6: Super Bulky8 to 12.75 mm11 to 17
7: Jumbo12.75 mm and larger17 and larger

For more information about yarn weight and how it relates to needle size and gauge, be sure to read our Guide to Yarn Weight.

How to Know Which Needle Size to Use

There are several ways to determine which needle size to use with your yarn.

Read the yarn label. The first way is to read the yarn label, sometimes called the ball band. The label will have all sorts of information about the yarn, including the recommended needle size. The label might list one size or a range of sizes.

Consult a yarn weight chart. If you don’t have a yarn label, you can consult a yarn weight chart. These charts will list the recommended needle size range for each type of yarn. These charts are a useful starting point, but you’ll still need to consult your pattern and make a gauge swatch to know for sure.

Check the pattern. If you’re following a pattern, it will usually list the recommended needle size. Keep in mind that everyone knits with a slightly different tension, and you may need to adjust the needle size to get the gauge you want. If you are a tight knitter, you may need to move up a needle size. Or, if you are a loose knitter, you may need to go down a needle size.

Make a gauge swatch. The best way to know which needle size to use is to knit a gauge swatch. A swatch will confirm that you’re using the right needle size for your project. If your swatch gauge matches the pattern gauge, you’ll know you have the correct size needles.

gauge ruler on a swatch made with blue yarn on a gray background
a needle gauge tool

How to Know What Size Needles You Have

There are a few different ways to determine the size of your needles.

Check the needle label. The most accurate way to know the size of your needles is to check the label. Most commercial needles will be clearly labeled with their size.

Use a needle gauge. If the needles aren’t labeled, or their label has worn off, you can use a needle gauge to determine the size. A needle gauge is a small wooden or plastic tool with holes of different sizes. To measure your needle, slip the needle into the holes until you find the one that matches.

Measure the length with a ruler. If you need to measure the needle’s length, you can measure the needles with a ruler or tape measure. Whether you’re measuring straight needles, circulars, or DPNs, measure from needle tip to needle tip.

Needles Sizes FAQs

Here are some more commonly asked questions about knitting needle sizes.

How many knitting needle sizes are there?

There are so many sizes of needles, and each brand offers its own range. You can find needles as small as 1mm or as large as 35mm, and everything in between.

How do I know what size needle to use?

There are a few different ways to determine which needle size to use with your yarn. The first way is to read the yarn label and see what size it recommends. The second way is to consult a yarn weight chart and see what size is usually used with your yarn. The third way is to check the pattern and see what size it recommends. However, the best way to know for sure is to knit a gauge swatch.

How do I know what size needles I have?

There are a few different ways to determine the size of your needles. The first way is to look at the needle itself, and see if a size is written on it. The second way is to measure it with a needle gauge tool.

What knitting needle size is best for beginners?

We recommend that beginners start out with worsted-weight yarn and a pair of size 8 (5 mm) straight needles. The length will depend on your project, but 10 inches is comfortable for most beginners.

What knitting needle size is best for socks?

For sock-weight yarn, we recommend using size 2 (2.75 mm) needles or smaller. The smaller needles will give you a tighter gauge, and the socks will be more durable.

More Knitting Guides

To learn more about knitting, check out these related articles:

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Waheeda Asif

Friday 18th of November 2022

Hi Sarah. Your article on needles was very helpful . Infact i was searching for such information. Thanks