What Sizes Do Crochet Hooks Come In?

    by Joanna Swanson

    About the Author

    Based in Laramie, Wyo., Joanna Swanson has been writing in her professional life since 2004. She currently writes for various websites and enjoys reading a wide variety of books. Swanson holds a bachelor's degree in business administration from the University of Wyoming.



    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.