Crochet Hook Size Conversion Chart

crochet hooks in various sizes

Crochet hook sizes can be a bit confusing, especially if you are either new to crochet or live outside the U.S. and are trying to find the right size to follow an American pattern. I’ll explain the American crochet hook size system, and provide a conversion chart so that you can crochet with ease, no matter where you are!

Variety of crochet hooks

American Crochet Hook Sizes

American crochet hooks go by two names: a letter and a number. For example, the crochet hook size that is most commonly used for worsted weight yarn is an ‘H’, which is sometimes called a ‘size 8’. From an international point of view, this number is incredibly confusing! Most countries identify crochet hooks by their size in millimeters (mm). A size H crochet hook is 5mm, which as you can notice, doesn’t clearly line up with the number ‘8’. However, this confusing notation isn’t a problem if you reference a conversion chart when you are ready to crochet.

Crochet Hook Conversion Chart

There’s a terrific printable chart available at the LoveCrochet website. Not only does it convert between American letter/number sizes and mm – it also “translates” between American and Australian yarn names, and American and British crochet terms. Very handy!

Get it here.

Use the chart to find the size called for by your pattern, and you will be able to identify the size (in mm) that you should use. This should allow you to find the hooks you need to crochet using American patterns, no matter where you are!

The chart also reveals another slightly confusing aspect of crochet hook sizes: you will notice that the difference in mm between two hook sizes is not a consistent difference. For example, the difference between a ‘B’ and a ‘C’ crochet hook is .5mm. However, the difference between an ‘H’ and an ‘I’ crochet hook is 1.0mm. This can make it difficult to remember all of the conversions, so be sure to check each hook size that you would like to convert. Usually, both the American size and the size in mm are written on the crochet hook package, so that is a convenient place to check when you are making a purchase.

There are occasionally some differences in sizing according to various brands, but the chart includes the most common ones.

Now, you’re ready to start converting and crocheting!


  1. Adele Gilmore SAYS...

    Thank you for this chart.

    By chance do you have one for tiny hooks?


    • Hi Adele-
      Not one for tiny hooks, yet!

  2. liz SAYS...

    Hey there, I am making a beanie with an F hook. The pattern calls for J but it looked whack with a J; so I used the F. With the J hook, I can stop increasing size at sc9, 2sc in one. In your opinion, what does that convert to using my F hook? I was thinking adding 5 more rows, but would appreciate a second opinion.

    • Hi Liz-
      Changing gauge as it relates to a pattern is a complicated question… unfortunately, there’s no ‘one size fits all’ answer. You’ll have to experiment, do some calculations and see if it’s working for you!

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  4. Gale SAYS...

    Hi, I am reading a pattern that calls for a Boye Steel Hook Size 1. I live in Canada and we do not have that brand of hook. Could you please tell me what size hook I would use?

    Thank you very much


    • Hi Gale! Ah, I see… too tiny for my chart! This page says a Boye is 2.75mm!

    • Adrienne SAYS...

      A 1 is a steel 2.25 mm hook , Adrienne

    • Anonymous SAYS...

      A steel crochet hook 1.00 mm is a size 12 steel hook. Hope this helps you out.

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  6. My SAYS...

    Hi! Your chart has been very helpful. I have a question though. I have a pattern that calls for a C hook (2.75mm) which I don’t have. I do have a steel size 1 hook which is 2.75mm and wanted to know if I could use the steel hook since it’s the same mm? Thank you.

    • That’s a really interesting question! Although my steel hooks are much smaller than a size C, my gut says that if you have one in the same mm size, then you can use it! I would pop by a store and look at a size C in person, though, just to make sure your size 1 is in the same ballpark.

    • Anonymous SAYS...

      Yes they are the same size

      • Jennie SAYS...

        What are the same size

  7. Jane SAYS...

    only one i found i understood, thank you

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  9. Laura Ettinger SAYS...

    I have a Lee Wards size 0. What is that equal to with a susan bates?

    • Hmm, I’ve never heard of Lee Wards. Do you have reason to believe the sizing is different than Susan Bates?

  10. Cynthia SAYS...

    I was wondering if maybe you could help me, I am about to start working on a table cloth, and the pattern calls for a “Milward Stell Crochet Hook No. 5”. I cannot find a conversion for the Milward to just plain mm, I have seen 1.75 mm and then 0.75 mm. Do you know anything about it?

    • My guess is that the pattern is referring to a Steel Hook size #5. Those are not included on this chart, but they are sold in stores. I don’t think the brand name is very important.

    • Adrienne SAYS...

      A 5 in a Milward which is a steel English needle is the same as F in a Susan Bates or a Boye

  11. sarahy j. SAYS...

    hi tracy 🙂 am making a shrug, the pattern ask for a n hook but i only have an L hook right now .do you think it would make a big difference on the work if i use a L hook instead of an N hook? thanks a bunch 🙂

    • Hi Sarahy- I always recommend that you use the hook size that gets you the gauge recommended in the pattern. Otherwise, you may end up with a shrug that doesn’t fit!

      • sally k SAYS...

        I have a pattern asking for a 3mm hook. It’s for a baby sweater, hat and booties. Your chart doesn’t convert 3mm, any suggestions?

        • I would look online for a 3mm hook- different brands tend to offer different sizes.
          Otherwise, be sure you are doing a gauge swatch, you may find you need a different size, anyway!

  12. Amanda SAYS...

    Hi, your chart is really helpful but i have a small issue i am running into. I bought my crochet hooks online so they were shipped from China and i live in the U.S. and i looked at your conversion chart and back at my hooks and noticed there is a 0.5mm increase between my hook sizes until it gets to 7.0mm then it goes straight to 8.0mm other than that my smallest is a 2.0mm which i don’t think ill use much. But i am trying to make a newborn beanie for my nephew who is due next month and it requires a J hook with the yarn i am using but i am having trouble converting it, and i think it has to do with my hooks coming from China but i am not sure. Can you help???? Any thoughts or help would be appreciated i am clueless right now…

    • If your yarn called for a size J hook, and yours are marked in mm, then you need a 6mm hook. The increases between sizes aren’t consistent, so don’t worry about that.

  13. Janice Ramirez SAYS...

    I ambos en México and i am wanting to make adult socks it calls for a 4mm G.what is that size in regular crochet needles?

    • That could also be called a size 6. Did you see the link to the chart?

  14. tmana SAYS...

    The issue I’m finding is that different brands of hooks have different size standards for each US letter. A lot of my older hooks don’t have metric sizes stamped on them. That all being said, if you choose your hook and yarn to the pattern’s gauge, you should be OK.

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  16. Brooke Scherlie SAYS...

    Why is a 4.0 a G hook on most charts but an F hook in Addi Swings? My British pattern is calling for a 4mm (US G/6) hook. My Addi 4.0mm hook is an F! Should I just typically go by mm sizing? It seems more precise…Thanks!

  17. Rose SAYS...

    I have susan bates crochet hook
    D 3.25 E 3.50 F 3.75 G 4.00
    I bought the crochet lite hooks
    But the mm is off
    D 3.00 E 3.50 F 4.00 G 4.50

    So if im using D 3.25 mm
    in susan bates can i use
    The D 3.00 mm in the crochet lite

    • When in doubt, always follow the mm size – not the letter.

  18. My pattern calls for a 3 mm crochet hook, but I didn’t see the conversion for that on your chart! Would you please tell me what the conversion is for a 3 mm crochet hook?

    • 3 mm isn’t a standard size and so doesn’t have a letter correlation. You can still get them – they just won’t have a letter on them.

    • You’ll just need to do a test swatch to make sure the gauge is correct – that’s the most important thing when stitching clothing in order to get the fit right.

  19. Carol SAYS...

    Bought yarn in Ireland with a 7mm hook. The conversion chart it between a K and L. Not much help. What is it exactly?

    • It really depends on what you’re using it for. Remember – the size on the label is just a guideline. Are you making a scarf and you want it soft and drapey? Go with the larger hook. Are you making a stuffed animal and you want a tight fabric with smaller holes? Go with the smaller hook.

  20. Jennie SAYS...

    Can I use a size G5 in place of a G6?

  21. Anonymous SAYS...

    So where is the conversion chart???!!!

    • Click on the link where it says “Get it here.”

  22. Karen Holmgaard SAYS...

    I have a Susan Bates aluminum hook that states it is a US G6/4mm and a Boye aluminum hook that reads G/6-4.35 mm. The pattern calls for a G hook. Which one should I use?

    • Crochet a gauge swatch and see which one you like better. The hook size in a pattern is always just a suggested starting place.

  23. Anonymous SAYS...

    I’m using a size 11 English hook to make a tablecloth what is the metric conversion

    • Most of the time if the hook has a number on it (as opposed to a letter) that number IS the number of mm, so it’s already metric.

  24. Judy Rasey SAYS...

    I have a pattern that calls for 1/6 mm hook using worsted wt yarn. What size hook do I want to use?

    • 1/6 mm would be awfully small. 6 mm (size J) would be more common for worsted weight. Maybe it’s suggesting a size I (5.55 mm) or J (6 mm)? Use whichever size gets you the specified gauge. Remember that the hook size requirement is always a suggestion. If the finished size is important (like for a garment) you really need to stitch a gauge.

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