Crochet Hook Size: Getting the Size of Your Crochet Hooks Right

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Like with all crafts, it is important that you get your crochet tools right. When you start out crocheting, there are a lot of things you will need to get your head around. Not only do you know about the different types of crochet hooks, but you will also need to know which crochet hook size to use.

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You would think that picking the right size for your crochet project is easy. But think again… Your crochet pattern might suggest a crochet size. Likewise, your yarn ball label might indicate a hook size to use.

However, before you grab what you think is the correct crochet hook, you must first check out which terminology your pattern is using.

Next, you need to check out they type of crochet hook you are using – is it made from aluminium or steel?

Getting confused?

Don’t worry, I will try and demystify crochet hook sizes in this article.

Is there a standard crochet hook size?

Unfortunately, crochet hook sizes are not standardized, that’s why it can be a little complicated and at times frustrating when you try to get the gauge with the size suggested in the pattern or on the yarn ball label.

This is because crochet hook sizes can differ according to brand, material, and country where the hook is made.

But even though there is no standard sizing for crochet hooks, there are at least 4 universally known measurements that will tell you exactly what size of crochet hook you should use.

These measurements are as follows:

  • US sizes
  • UK sizes
  • Metric sizes
  • Japanese sizes

US Size Crochet Hooks

Sizes of crochet hooks made in the USA have letters or numbers as designators. Typically, the sizes will start from B and go through to Q. B will be the smallest hook size. In fact, the further you go through the alphabet, the larger the hook size.

With regards do standard crochet hooks (not steel hooks), the numbers will go from up to 16.

UK Size Crochet Hooks

Crochet hook sizing in the UK is also indicated by numbers, usually ranging from 14 through 000. However, the larger the number, the smaller the hook. Canada uses the same measuring system.

Metric Size Crochet Hooks

Metric size hooks are probably the most accurate sized crochet hooks. This is because the diameter of the hook shaft determines the size of the crochet hook and thus the size of your stitches.

The metric sizes range from a diameter of 2 mm all the way up to 20 mm. You might even be able to find hooks that are even bigger!

You will typically see the metric sizing used in European crochet patterns as well as patterns from Australia and New Zealand.

Japanese Crochet Hook Sizes

Japanese crochet hooks have steadily gained more popularity thanks to the many amazing patterns you can find in Japanese pattern books, etc.

And let’s not forget the many incredible amigurumi patterns you can try out…

Japanese crochet hooks use a number system starting from zero as the smallest hook. It will typically go up 15.

Regular Crochet Hook Size Conversion Chart

To make it a bit easier for you, we have included a Conversion Chart for the various crochet hook sizes.

METRIC SIZE
US SIZE

UK SIZE

JAPANESE SIZE

2 mm

 A-0

14

0

2.25 mm

B-1

12

2.5 mm

12

1

2.75 mm

C-2

2

3 mm

11

3

3.25 mm

D-3

10

4

3.5 mm

E-4

9

5

3.75 mm

F-5

6/7

4 mm

G-6
8

7

4.5 mm

7
7

8

5 mm

H-8
6

10

5.5 mm

I-9
5

 11

6 mm

J-10
4

13

6.5 mm

K-10 1/2
3

15

7 mm


2

8 mm

L-11
0

9 mm

M-13
00

10 mm

N-15
000

Steel Crochet Hook Sizes and Crochet Thread Sizes

Typically, you will only use steel hooks when using very thin or fine yarn such as crochet threads or lace-weight yarns.

Actually, you will often see these thin crochet hooks referred to as “thread hooks”.

Furthermore, when it comes to steel crochet hooks, the sizing is reversed – a higher number means a smaller hook, and vice versa.

In fact, you might notice that crochet threads are sized in the same way – a smaller number means thicker thread and vice versa.

On the other hand, steel crochet hook and regular crochet hook sizes have one thing in common: the numbering varies depending on the country of origin.

Here is a steel crochet hook size chart for you to use as a reference when you need to use steel crochet hooks:

Steel Crochet Hook Size Conversion Chart

METRIC SIZE
US SIZE

UK SIZE

JAPANESE SIZE

0.5 mm

14

0.6 mm

12

0.75 mm

14

10

0.9 mm

13

7

8

1.00 mm

12

6 1/2

6

1.25 mm

10

5 1/2

4

1.50 mm

8

4 1/2

2

1.75 mm

6
3 1/2

0

2 mm

4
2 1/2

2.25 mm

2
1 1/2

2.5 mm



2.75 mm

1
1

3 mm



3.25 mm

0
0

3.5 mm

00

How to Choose the Correct Crochet Hook Size

The first thing to do when determining the crochet hook size to use, is to check which terminology your pattern is using. Most likely, it will be either a US or a UK pattern.

You can learn more about US and UK crochet terminology here: Crochet Terms: The Differences between US vs UK Crochet Terms Explained.

Secondly, you will need to make a gauge swatch. I am afraid there is no getting away from this…

Once you have completed the gauge swatch, compare it to the gauge information given in the pattern.

If you are not familiar with gauge swatches, we have an informative article which you can find here: Crochet Gauge: The Ultimate Guide to Getting Gauge Right.

Finally, keep in mind that the material used in your crochet hook may influence your crocheting. So, always make your gauge swatch with the hook you want to use for your project.

Likewise, if you are like me, you might crochet looser during the summer when it is hot then on a cold winter day. Unfortunately, that may mean that an old gauge swatch may not be correct for a project you want to do now.

Happy crocheting!

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