5 Things You Should Know About Crochet Hook Sizes

Lindsey lists 14 Comments

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Letters are for the US only
The letter designations you may see on crochet hooks (D, E, F, H, etc) are only used in the United States. Crochet hooks from other countries aren’t labeled that way.

The mysterious number 7
In addition to letter designations for crochet hooks, number designations can be used. So an H hook is often referred to as an 8. A G hook is often referred to as a 6. But between a G/6 and H/8 is the mysterious size 7 hook. Why doesn’t it have a letter designation? I’m sure there is some perfectly valid historical reason, but I prefer to think of it as just some other wacky way the universe makes life more interesting.

Millimeters are best…
The most accurate way of designating hook size is using millimeters. So an H hook is 5.0 mm and a G hook is 4.0 mm and a 7 hook is 4.5 mm. If you are going to choose just one method for picking hook size use millimeters. This is especially helpful size many companies will use the same letter designation for different sizes. I have two F crochet hooks from the same company. One F hook is marked as 3.5 mm, and the other is marked as 4.0 mm. I never would have noticed the size difference if I had only looked at the letter designations.

…Except when they’re not
A millimeter should be the same the world around, but every manufacturer’s equipment differs slightly. So my 1 mm crochet hook from one company is actually smaller than my .9 mm crochet hook from a different company. Yes, the .9 mm should be smaller, but it’s not. Frustrating, ain’t it?

So, don’t change hooks
So what’s the big lesson here? Don’t change hooks in the middle of the project (unless it’s called for, of course). There is so much variation between companies and even within companies. Pick one hook to use for your project (and guage swatch), and stick with it.

Comments 14

  1. I am newer to crochet and that question of the numbers and letters have been on my mind for a little bit of time, this was a timely post. One of the things I am experimenting with is playing around with different hooks to help with shaping certain projects I am designing. what are your thoughts on using various hooks to shape the item you are creating?

  2. Lindsey Post

    If it’s an item just for me, then I have no problem by accomplishing shaping using different hook sizes. If it’s a pattern I’m putting out, I’d hesitate. First, I worry that crocheters might be turned off by the need for multiple hooks. That may be a silly concern since we all seem to have houses overflowing with crochet hooks anyways. Second, if it’s a fitted item, like a sweater, then the crocheter would have to worry about matching gauge with the first hook and with the second hook. Let’s say I get 6 sc = 1 in with a G hook and 7 sc = 1 in with an H hook. Another crocheter might be able to easily match the gauge with the G hook, but what if they get 6.5 sc = 1 in with the H hook? It’s doable, but it requires more gauge swatches.

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  4. I am a knitter who is just beginning to learn to crochet. I had to purchase a “Size 10” steel crochet hook for a class I’m taking, and ordered a set and an individual hook online. In the set, the “Size 10” crochet hook is also labeled as 1.15mm in one brand, but the individual “Size 10” hook, made by another company, is labeled as 1.3mm. When I look on the Craft Yarn Council website, there’s no “Size 10” listed, per se, but there is a size “J-10,” which is 6mm. So confusing! I’ve never encountered such issues with knitting needles, so why can’t crocket hooks get their act together??? 😉

  5. Lindsey Post

    I feel your pain. With the steel hooks you’ll probably notice different countries of manufacture. My Japanese steel crochet hooks are very different when you compare the mm sizing to my US ones. Your best bet is to just go for mm sizing. Good luck!

  6. Thank you for this information! It’s a relief to know I’m not crazy- about hook sizing, anyway 🙂

  7. Jean I think a G or an H size hook is a good size to start with using a regular worsted weight yarn or a medium weight cotton yarn.

  8. Just saw your post while in Round 2 of a cap (for me) using a Yulip ETIMO Size 7 (4.0mm). The pattern called for G/7 (4.5mm).

    After reading your post, I want to change to the 4.5mm thereby sticking with choosing mm size over letter size.

    Will my cap really be affected that much, should I change to 4.5mm at the beginning of Round 3???

  9. Lindsey Post
  10. I have a question! I’m relatively knew to crochet and I started on a blanket but somewhere along the way of moving it around my 5.5mm hook I was using has gone missing! It came in a pack I bought so they’re all the same brand (Susan Bates Silvalume Hook Set). Can I use the 5.0 mm hook to continue the blanket or will that mess up the whole thing?

  11. Lindsey Post

    Your gauge (the size of your stitches) will change slightly if you use the different hook size. Best to go out and buy another one. (If it makes you feel better, I own around 3 or 4 hooks in each size.)

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