So how do you know what kind of circular needle to use for your project?
Well, there's two main ways to think about this, and one is to think about the size of the project that you're knitting, and the size of the yarn that you're using.
So your yarn is a great place to start. All balls of yarn will come with a ball band and it will tell you, amongst other things, the desired gauge that the manufacturer of the yarn thinks works well for the yarn. So like what, how many stitches per inch you're going to be getting for an ideal fabric.
Now, that's just what they think. It's up to you. If you know that you're using their yarn to knit something a little denser then you're going to have more stitches per inch, and if you want to use their yarn to knit something more loose and gauzy, you're going to use bigger needles than called for.
Another thing to keep in mind is are you a loose knitter or are you a tight knitter?
For example, this is a fingering weight yarn where they recommend having between 28 and 32 stitches over 4 inches. So when you take a gauge swatch, you would divide how many stitches you have in a 4 inch swatch by 4 and that will tell you how many stitches you're getting per inch.
So that's their recommended gauge. And then they also recommend that you get that gauge with anywhere between a US 1 and a US 3 diameter needle.
For me, I know that I'm a loose knitter so I would go down to the bottom end of that range and swatch it with maybe a 1 or even a 0. I know for me that knitting with size 0 needles on fingering weight yarn gets me a good fabric, but for you, you might be a tight knitter or you might hold your needles differently, so always do a gauge swatch.
So that's how you know what diameter needle you want to start with. And you can always test the diameter of you needle with one of these wonderful knit checks.
They make a bunch of different kinds of these. This is the cheap one that's easy to find everywhere.
You would check the diameter of your needle by simply placing it in the right hole. This is too small for the 13 hole, so it fits perfectly in the 15 hole. So I know that this is a US 15. So that's how to choose the diameter of your needle.
The next thing to think about with circular knitting is the length of your needle. So one thing that's good to know is that you can always fit more stitches on your needle than the needle is long, but you can't fit fewer.
So if you're really stretching your stitches to go all the way around to go from tip to tip and they've got a lot of space, don't stress your fabric out in that way. Move to a shorter needle.
We've got really, really long needles, and really, really short needles, and everything in between.
So if you're knitting a giant sweater, this would be really appropriate. All the stitches can fit on that needle.
If you're knitting a cowl, this would be really appropriate. But if you're knitting a sock this would be too long.
So you have to think about the recommend gauge for the yarn, and what size diameter needle. And then you have to think about the length of your needle that's suitable for the size of the project that you're knitting.
And that's how to choose the right circular needle.