Knitting needle sizes and crochet hook sizes are commonly given as either metric or US, and if you're fortunate, both. The same applies to knitting or crochet patterns. Sometimes it's not so easy, so I always refer to my dependable conversion chart. I've also added a helpful table that converts inches to centimetres. I've rounded up, or down, the numbers to fit into the common knitting standards for most needle and cord lengths that you'll find at The Needle Store.Â
All super helpful for me, and I hope you find it useful too. I've saved this as a handy PDF that you can keep and refer back to as well.
|  Metric |
US Needle Sizes |
UK Old Needle Sizes (Imperial) |
US Hook Sizes |
UK Old Hook Sizes (Imperial) |
| 1.50mm |
000 |
17 |
8 |
-- |
| 1.75mm |
00 |
15 |
6 |
-- |
| 2.00mm |
0 |
14 |
A/0 |
14 |
| 2.25mm |
1 |
13 |
B/1 |
13 |
| 2.50mm |
1 1/2
|
-- |
-- |
-- |
| 2.75mm |
2 |
12 |
C/2 |
12 |
| 3.00mm |
2 1/2
|
11 |
-- |
11 |
| 3.25mm |
3 |
10 |
D/3 |
10 |
| 3.50mm |
4 |
-- |
E/4 |
-- |
| 3.75mm |
5 |
9 |
F/5 |
9 |
| 4.00mm |
6 |
8 |
G/6 |
8 |
| 4.50mm |
7 |
7 |
US7 |
7 |
| 5.00mm |
8 |
6 |
H/8 |
6 |
| 5.50mm |
9 |
5 |
I/9 |
5 |
| 6.00mm |
10 |
4 |
J/10 |
4 |
| 6.50mm |
10 1/2
|
3 |
K/10 1/2
|
3 |
| 7.00mm |
10 3/4
|
2 |
K/10 3/4
|
2 |
| 7.50mm |
-- |
1 |
-- |
1 |
| 8.00mm |
11 |
0 |
L/11 |
0 |
| 9.00mm |
13 |
00 |
M/13 |
00 |
| 10.00mm |
15 |
000 |
N/15 |
000 |
| 11.50mm |
-- |
-- |
P/16 |
-- |
| 12.00mm |
17 |
-- |
|
-- |
| 12.75mm |
-- |
-- |
US17 |
-- |
| 15.00mm |
19 |
-- |
-- |
-- |
| 15.75mm |
-- |
-- |
Q |
-- |
| 16.00mm |
-- |
-- |
-- |
-- |
| 19.00mm |
35 |
-- |
-- |
-- |
| 20.00mm |
36 |
-- |
-- |
-- |
| 25.00mm |
50 |
-- |
-- |
-- |
| 30.00mm |
60 |
-- |
-- |
-- |
| 35.00mm |
70 |
-- |
-- |
-- |
 Â
|
Inches
|
Centimetres
|
|
3.5"
|
9cm
|
|
5"
|
13cm
|
|
6"
|
15cm
|
|
9"
|
22cm
|
|
10"
|
25cm
|
|
12"
|
30cm
|
|
14"
|
35cm
|
|
16"
|
40cm
|
| 20" |
50cm |
|
24"
|
60cm
|
|
32"
|
80cm
|
|
40"
|
100cm
|
| 47" |
120cm |
| 60" |
150cm |
