UK and US hooks – names and sizes

Hooks themselves don’t vary the world over, but how people talk about them do. The UK and the US use different naming conventions for crochet hooks so I’ve posted below a chart to help you, sourced from Wikipedia.

Millimeter range Crochet hook size (letter)           Crochet hook size (numeric)
2.25 mm B 1
2.75 mm C 2
3.25 mm D 3
3.5 mm E 4
3.75 mm F 5
4 mm G 6
4.5 mm 7
5 mm H 8
5.5 mm I 9
6 mm J 10
6.5 mm K 10.5
8 mm L 11
9 mm M/N 13
10 mm N/P 15
12.75 mm
15 mm P/Q
16 mm Q
19 mm S
25 mm

2 thoughts on “UK and US hooks – names and sizes

  1. What drives me batty isn’t the US/UK conversion, but the fact that different US manufacturers (or sellers, I supposed, since most of our stuff is made overseas) can’t agree on the size for certain letter hooks! For example, I’d always assumed that a G should be 4.00 mm, but recently came across a pattern that called for a G and had a note that it should be the 4.25 mm! I’ve hunted high and low and can’t find a 4.25 G. I’ve sometimes had a bit of trouble with gauge with a G, and now I’m wonder if this is why. Although 0.25 mm doesn’t seem like it would make much of a difference.

    • Argh that’s something I didn’t know. I had noticed that the odd pattern here and there didn’t work with the specified hook size, leading me to change it. I have never seen a 0.25 hook either and tbh I’d probably ignore that little size difference. :>


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