What Sizes Do Crochet Hooks Come In?
The size of a crochet hook is determined by its measurement in millimeters. The crochet hook size is selected based on the size of yarn being used. The United States has a different labeling system than the United Kingdom and Canada do. Some hooks are only labeled in U.K./Canadian sizes with no U.S. equivalent or vice versa.
2 mm to 2.75 mm
At 2 mm, there is no U.S. size, but in the U.K. and Canada, it is labeled 14. A hook size of 2.25 mm is labeled B/1 in the U.S. and 13 in the U.K. and Canada. A hook size of 2.5 mm has no U.S. label, but is labeled 12 in the U.K. and Canada. A hook size 2.75 mm is known as C/2 in the U.S. but has no U.K./Canada equivalent.
3 mm to 3.75 mm
There is no U.S. hook at 3 mm, but the U.K. and Canada label it 11. At 3.25 mm, the U.S. has size D/3, and the U.K. and Canada have size 10. 3.5 mm is known as E/4 in the U.S. and as 9 in the U.K. and Canada. At 3.75 mm, there is no U.K./Canadian equivalent, but the U.S. labels this size F/5.
4 mm and 4.5 mm
A hook measuring 4 mm is known as G/6 in the U.S. and 8 in the U.K. and Canada. A hook measuring 4.5 mm has no U.S. size but is a 7 in the U.K. and Canada.
5 mm and 5.5 mm
A 5 mm hook is called H/8 in the U.S. and 6 in the U.K. and Canada. A 5.5 mm hook is called I/9 in the U.S. and 5 in the U.K. and Canada.
6 mm and 6.5 mm
A 6 mm hook is J/10 in the U.S. and 4 in the U.K. and Canada. A 6.5 mm hook is K/10.5 in the U.S. and 3 in the U.K. and Canada.
7 mm to 10mm
From 7 to 10 mm, there only exist crochet hooks at the integer measurements, 7, 8, 9 and 10. The U.K. and Canada call a 7-mm hook a 2, and there is no U.S. equivalent. A hook measuring 8 mm is L/11 in the U.S. and 0 in the U.K. and Canada. A hook measuring 9 mm is M/13 in the U.S. and 00 in the U.K. and Canada. A hook sized 10 mm is N/15 in the U.S. and 000 in the U.K. and Canada.
16 mm and 19 mm
For these large crochet hook sizes, there are no U.K./Canadian equivalents. A 16-mm hook has two U.S. names, P/16 and Q. A 19-mm hook is called S.