Most patterns will give you a gauge for the pattern in order to have your finished article turn out the same size as that of the designer. This is important because otherwise you’ll put in loads of work on a garment and it just might end up really huge or really tiny, depending on how your gauge compares to that of the designer. Here’s how to check your gauge.
Choose the yarn and needles you intend to use for the project. Cast on a few stitches. I like to do 30. Knit 3 rows. On the fourth row, knit 3 stitches, purl to the last 3, then knit those last three. On the fifth row, knit across. For the sixth row, repeat round 4. Continue in this manner until you have about 6 inches of knitting, then knit 3 rows at the end. Bind off. This is called a gauge swatch.
Once you’ve knit your gauge swatch, you need to measure it. For a long time, I just used a measuring tape to do this. I’d set the tape on top of the knitting and count the stitches over a span of either 2 or 4 inches. Now, I have this tool, which I can lay on top of my swatch and count the stitches in the cutout, which is a 2-inch L shape (for stitches across and rows up and down).
So… you’ve knit your gauge swatch and yours matches up with the pattern says you need. That’s great! You’re ready to start knitting with the assurance that your garment will fit as intended. But what if your stitches aren’t the same as what the pattern says?
That’s easily fixable. First you have to know whether your count is more or less than what the pattern calls for. If your pattern calls for “18 stitches over 4 inches,” simple division tells you that that’s 4.5 stitches per inch. It’s easy to think that if you get 4 or 5 stitches per inch, that’s “close enough.” This just isn’t the case. Think about it: an adult sized sweater is 30 inches or more around. If the gauge for the pattern is 4.5 stitches per inch, that means for a 38 inch sweater (random number), you need to cast on 171 stitches. If your gauge is 4 stitches per inch (and you don’t correct it, which I’ll explain how to do in a minute), then those same 171 stitches will give you a sweater circumference of 42.75 inches. That’s a lot bigger than the 38 you were going for! Looking the other way, if you’re getting 5 stitches per inch, those 171 stitches are going to give you a sweater that’s 34.2 inches. That’s also no good. So you can see, it’s really important to be dead on with your gauge if you want the garment to fit as expected.
Fixing your gauge for the project is as easy as swapping out your knitting needles. Using the example above, let’s say your gauge is 4 stitches per inch using the needle recommended in the pattern and on the yarn label. The pattern requires 4.5 stitches, so this means you’re not getting enough stitches per inch; yours are too big. Swap your needle out for one of a smaller size. This will make your stitches a bit smaller, and you’re likely to get the gauge pretty easily with just one size difference. The exact opposite is true if you’ve gotten 5 stitches per inch using the subscribed needles. You have too many stitches, which means yours are too small. Try a bigger needle.
Of course, you can always adjust a pattern instead of adjusting your stitches if you want, but that’s a lot more complicated and requires a fair amount of math. I prefer to adjust my needles instead.
I hope this helps you understand gauge and why it’s important, but more important, how to make sure you get it right and how to fix it if you don’t.