The UK and US use numbered or lettered hook sizes in their patterns rather than a standardized measurement. What are the conversions between the hook sizes depending on whether I'm using US or UK patterns?


For hook sizes, it's always best to refer to the size of the hook in mm, if possible. This should be standard across all countries. Metric sizes are used in many countries including Australia and New Zealand. UK sizes are generally used in the UK and Canada. US sizes are generally used only in the US.

The equivalents (when applicable) are below. Note that some sites give different size conversions for the same hook and not all mm sizes are available in every system, which is why some sizes are listed under more than one mm size.

Crochet Hook Conversions:

mm size ----- US -------- UK

2.00 mm ---- 0 ------ 14  
2.25 mm --- 1/B ----- 13  
2.50 mm ---- 2 ------ 12  
2.75 mm --- 2/C ----- 11/12  
3.00 mm ---- 3 ------ 11  
3.25 mm --- 3/D ----- 10  
3.50 mm --- 4/E ----- 9  
3.75 mm --- 5/F ----- 9  
4.00 mm --- 6/G ----- 8  
4.50 mm ---- 7 ------ 7  
5.00 mm --- 8/H ----- 6  
5.50 mm --- 9/I ----- 5  
6.00 mm --- 10/J ---- 4  
6.50 mm -- 10½/K ---- 3  
7.00 mm --- n/a ----- 2  
7.50 mm --- n/a ----- 1
8.00 mm --- 11/L ---- 0  
9.00 mm -- 13/M/N --- 00  
10.0 mm -- 15/N/P --- 000  
15.0 mm --- P/Q ----- n/a
16.0 mm ---- Q ------ n/a
19.0 mm ---- S ------ n/a
  • If there are other systems of hook measurement not included here that would be useful, please let me know and I will add them! I want this to be a useful FAQ for crochet hook size conversion.
    – Catija
    Apr 27 '16 at 17:26
  • I am very happy that you have the text as supposed to a picture. This should help get more view for sure.
    – Matt
    Apr 27 '16 at 18:08
  • Please expand your table to include hooks smaller than 2mm. In my country they are described in milimeters, but I think their names were weird for UK and/or US Apr 27 '16 at 19:13
  • @jkadlubowska You mean like the tiny hooks used for lace tatting and crocheted jewelry making?
    – Catija
    Apr 27 '16 at 19:15
  • I've been doing some research @jkadlubowska and I'm afraid they're a bit out of my depth... There seems to be a lot of disagreement regarding the sizes of these hooks. There are at least two different charts of equivalents between the US sizes and their mm equivalents and two charts for UK to mm, so I'll have to do some more work before I can fully address that part of the sizing chart.
    – Catija
    Apr 27 '16 at 20:42

Please note that in Canada metric sizing is the predominant measurement used for crochet hooks; i.e. 1.00mm, 1.30mm, 3.00mm, 4.25mm, 5.00mm, 6.50mm etc. Very rarely these days is the U.K. system used in Canada.
Certainly, it would be less confusing and more helpful if the metric system were for crochet hooks around the world. It is already used in many areas. Hooks smaller than 2.00mm are made by a variety of manufacturers in full steel and steel with ergonomically made handles by a variety of manufacturers.

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