The size of a crochet hook depends upon its thickness because this is what dictates the size of the stitches you create. It's important to use the right size of crochet hook to give you the correct tension or gauge for your chosen pattern.
Crochet Hooks Are Sized Differently Around The World
In Europe and Australia, crochet hook sizes are usually described in millimetres whereas in the US, they are usually listed with a letter and/or a number. In Japan there is a slightly different numbering system and in the UK many crocheters still use an old imperial numbering system. You might also have inherited crochet hooks from a time when there were no standard sizes, it's not an issue and these may come in very handy if you need to adjust your tension you can buy a hook sizeing tool that will tell you what size they are. In the table below we have set out a table of hook sizes to help you compare the sizes of the hooks you have and what may be asked for in your pattern. This will help especially if you want to use use vintage patterns and when buying patterns online that may have originated in different countries. If you'd like to know more about how the size of your hook can be used to adjust your tension, why not read our article What is Crochet Tension?
Crocket Hook Size Conversion Chart
Metric |
US |
UK (Imperial) |
Japan |
|---|---|---|---|
2 mm |
3 mm |
4 mm |
5 mm |
2.25 mm |
B/1 |
13 |
3/0 |
2.5 mm |
C/2 |
12 |
4/0 |
3 mm |
- |
11 |
5/0 |
3.25 mm |
D/3 |
10 |
|
3.5 mm |
E/4 |
9 |
6/0 |
3.75 mm |
F/5 |
9 |
|
4 mm |
G/6 |
8 |
7/0 |
4.5 mm |
G/7 |
7 |
7.5/0 |
5 mm |
H/8 |
6 |
8/0 |
5.5 mm |
I/9 |
5 |
9/0 |
6 mm |
J/10 |
4 |
10/0 |
6.5 mm |
K/10.5 |
||
7 mm |
- |
||
8 mm |
L/11 |
||
9 mm |
N/13 |
||
10 mm |
P/19 |
