Crochet Hook Sizes

By Rachel Choi – 10 Comments

Lots of crocheters get confused about crochet hook sizes since hooks are labeled with variations of letters or numbers. Here is a table that I hope will help everyone convert millimeter hook sizes to popular letter and number sizes.

As you can see in the chart, U.S. hook sizes use letters and numbers that are not very consistent. Millimeters are more reliable in labeling the size of a hooks since it is an actual measurement of how big or small a hook is. All patterns that I publish on CrochetSpot will have crochet hook sizes in millimeters.

Crochet Hook Sizes

U.S. Size
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 1/2
8 mm L-11
9 mm M/N-13
10 mm N/P-15
15 mm P/Q
16 mm Q
19 mm S

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  1. Helen Ensor says:

    Thank you for showing how to do TSS I wanted to know how to make that stitch and now I do

  2. Annessa says:

    Thanks Rachel for the chart. It is very useful as my hooks are in mm not alphabet. But I do have a question for you, the yarn thread used for all hooks usually the same ones or different thread size for different hook size? i know there’s some yarn are thicker/more ply but can i actually use bigger size hook for a standard yarn ball? Thanks.

    • Rachel says:

      Hi Annessa!

      Honestly you can use any sized hook for any sized yarn or thread. But of course each hook size will give it a slightly different look, making your stitches tighter or looser. Most yarn packages can will tell you the recommend hook to use with that yarn. If you are using a crochet pattern, it should tell you what hook and yarn size to use as well. A good rule of thumb is to create a little square using the yarn you want with a certain crochet hook and see if it turns out the way you want it. If not, them choose and different hook and test that 🙂

      I’ll try and post a chart for the recommended hook size to use with different types of yarn!

  3. Annessa says:

    Thanks Rachel for the advise. : )

  4. Norliza Lias says:

    Hi Rachel…

    I’d try quite a number of hat patterns. But the results actually dissappointed me….they turned to be too small. My problem is now the largest hook I have is 3.5mm and most of the patterns use larger size hook. What can I do? Can I change sc to hdc or dc in order to make a bigger size hat or any opinion?

    • Rachel says:

      Hey Norliza!

      Sometimes you can use more than one strand of yarn together and that can make your hat bigger. If there is a gauge with the pattern, try making it with the hook you have and more than one strand of yarn held together.

      I hope that helps! 🙂

  5. Norliza Lias says:

    thanks Rachel i’ll try.

  6. Marcia Kirby says:

    Thank you. That helps! Marcia

  7. I found a U size, 25MM!!!!

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