It IS the size that matters

As those of us here in the US already know, US hook sizes are identified by a lettering system. We have our favorites for different yarns, for me H’s, I’s and J’s are great for worsted yarns, G’s and H’s work well for DK, and D’s , E’s and F’s are good for fingering. Whatever our choices, the lettering and sizes are all standard, right? Nope.

Pretty crochet hooks in various sizes

Take a look at Ravelry’s hook and needle chart. You can go to your Ravelry library, then click on “needles and hooks”, or you can just look at mine. The hooks are at the bottom, with metric sizes and US letters listed. Notice something funny near the large end of the hook chart? What’s with the M/N, N/P, and P/Q?

This post contains affiliate links (click here for more info). If you click these links and register or make a purchase, I may be compensated. 

A 9 mm hook is sometimes called an M, and is sometimes called an N. Not only that, but N can be either 9mm or 10mm! Even more dramatic, a P can be 10 mm or 15 mm, or…well, anything inbetween. The numbered sizes are even more confusing – a G hook, for example, is also a US size 6, which is 4 mm (because that makes sense, right?).

Here’s a Boye set, containing sizes L-P. The M is 9mm, N is 10mm, and the P is 11.5mm. They’ve avoided the confusing size numbers entirely. Now check out these hooks from Lion Brand: The Clover Amour onesshow alternate lettering, just like on Ravelry. If you scroll down, though, you’ll see the actual Lion Brand hooks are different: There is no M, but size N-13 is 9mm and size P-15 is 10mm!

Confused yet? Knitting needles are just as bad! What’s listed as a size 1 sock needle could be 2.5mm, or it could be 2.25mm, depending on the brand. There are half sizes, double (or more) 0s, and the larger sizes inexplicably start going in odd numbers only (until you get really large, of course).

So where did this mess come from? Really just a lack of a universal standard. Without any uniform standard, manufacturers created their own, which were all different. Over time, sizes have become more standardized, but as you can see there is still some discrepancy.

The Craft Yarn Council has worked with manufacturers to create a list of sizing standard, and to encourage prominent use of metric measurements. I think metric makes more sense, and the rest of the world is ahead of us in that respect. Why use arbitrary letters and numbers to indicate size, when you can use the actual size instead? After all, it is the size (not the arbitrary label) that really matters.



  • susi hahaj

    where can i get a sizer like the one pictured? i have my mom’s 70 year old hooks and some new ones i’d really like to compare. thanks

    • Pia Thadani

      There are actually lots of good options! Here are affiliate links for a few of them (If you click these links and make a purchase, I may be compensated):

      Here is the one in the picture – I bought mine at my LYS, but this is the same one at Amazon. It’s a Knitters Pride one, with a little hole at the top so you can string it onto a chain or clip if desired. You want to pay attention to how your gauge is marked. This one has mm on one side and US knitting needle sizes on the other. It does not have US crochet hook sizes marked, but you can figure those out by the size in mm.

      This Susan Bates one on Amazon has US knitting, US crochet, and mm sizing. It also has an L shaped cut-out which is used to measure your gauge.

      There are several other options on Amazon – I love the butterfly one!

  • Donnita Friberg

    I am so glad you wrote this article I have allot of hooks from different companies and each one is called a name and different size. I am so confused as to which hook is the right one for the project. none of them really match the charts so how can you tell which one is the right one. I give up!

    • Pia Thadani

      That’s one of the reasons gauge is so important! It doesn’t matter what hook you use, as long as your gauge matches the gauge specified in the pattern 🙂 I may write a pattern using a 4mm hook, but if you crochet tighter, you may need to use a 5mm hook to get the same size!

  • Sarah

    I live in the UK, so we label our hooks with how many mm they are. It has always puzzled me why the manufacturers of American hooks would need label them with a letter that corresponded to a size instead of just labeling the size. Now I know the letters are different across brands it makes even less sense!

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