How crochet hooks and knitting needles are measured for size

This might be something that is blatantly obvious to everyone else but me, but recently I found myself wondering exactly HOW are crochet hooks and knitting needles measured for size?

Hooks and needles are usually presented with their sizes given in millimeters (for example, a 5.5 mm crochet hook or a set of 7 mm knitting needles). But do those millimeters represent the hook's/needle's CIRCUMFERENCE or DIAMETER???

This issue actually came up when I was working the Harmony Shawl free pattern while camping. I didn't pack all my yarncrafting supplies for the trip, but I had a white plastic 6.5 mm K hook on hand. The pattern actually recommends an 8 mm L hook to create a fabric with a relatively large gauge, however, so I improvised by working each stitch way up on the handle of my K hook, at the point where the handle flattens out and gets wider (see photo below).

Working stitch up on the flattened hilt of a K hook to achieve a larger gauge.

But because I was camping without all of my supplies, I had no way to measure just how big of a stitch I was approximating by working them up on the hilt of my K hook. And then I realized that even if I'd had a measuring tape on hand, I actually didn't know whether the hook's size represented its circumference or its diameter. D'oh!

After we returned home, I searched the Internet for information about how crochet hooks and knitting needles are measured. This Wikipedia article had some interesting information, but it didn't fully answer my question because its statement "Hooks come in various sizes (measured in millimetres or fractions of an inch), according to the thickness of the needle" didn't clarify what it meant by "thickness of the needle." One could still interpret that as either the circumference OR the diameter! ARGH!

So, finally, I pulled out my measuring tape and an I hook (5.5 mm size) and tested the measurements out for myself. As best as I could tell, its circumference measured at 19 mm! That's obviously WAY more millimeters than 5.5!

Next I measured the hook's diameter, and as you can see in the photo below, it's fairly close to 5.5 millimeters.

So, at last, I have my answer for how hooks and needles get their size rating, and in the process, I learned something new. Now I won't have to take those size markings for granted anymore!

And if you've ever wondered the same thing about hook and needle sizes, I hope this post helped you as well. Happy yarncrafting!

P.S. And in case you're wondering what crochet hook size I actually was approximating by working up on the hilt of my K hook, according to the diameter sizing rule, as far as I can tell, that spot on the hook measures at about 10 mm, which is the equivalent of a size N hook.

Hexagon dishcloth free pattern Tunisian crochet

This was my very first attempt to do the Tunisian crochet technique after finding a 5mm Tunisian hook tucked away among the many sets of needles in my mother’s old knitting bag.

I don’t recall ever having seen her use this long afghan hook, although my memory is full of scenes watching her use standard hooks to create large, beautiful afghans for her home and to give as gifts.

Nevertheless, I wanted to try out this newly discovered hook, and a dishcloth seemed like a useful item to make as a learning piece (that was also of a manageable scale to finish quickly and avoid possible discouragement!).

This Tunisian Short Row Dishcloth pattern by Khebhin Gibbons is easy to follow and a great project for beginning Tunisian crocheters like me.

Because I am notorious for not following directions (something about my stubborn streak), instead of whip-stitching the edges together after making the final wedge in the hexagon as instructed, I simply slip-stitched the final edge to the beginning edge.

This brought the unbroken working yarn back to the outside of the hexagon, where I then switched to a standard I hook and added a ruffle made of four rows of a graduated picot trim for a lacy effect.