Gauge is the number of stitches and rows per inch that are created using a specific weight of yarn using a specific hook or needle size.
Checking gauge is a way for you to make sure your project ends up at the correct size and that you’re using (approximately) the same amount of yarn that is called for in the pattern.
Since no one crochets or knits in exactly the same way, it’s important to check gauge to make sure your project will turn out as expected.
What could happen if you don’t match gauge?
Your project won’t end up at the expected size
This isn’t a big deal for a dish rag or a scarf, or even a blanket. If those things are off by an inch or two, the finished product isn’t going to be ruined or unusable. For clothing projects, where size really matters, it could mean the difference between making an adult-sized hat or a child-sized hat.
You might not have enough yarn to finish your project
If your gauge is larger than called for, your finished piece will also be larger. If your finished piece is larger, you will use more yarn. If you did not buy enough yarn… well, you could be in trouble! Buying more yarn probably won’t be a problem if you’ve purchased a name brand yarn from a local big box store. On the other hand, you might have bought discontinued yarn on clearance or a delicious hand-dyed yarn with a limited skein run, which makes it next to impossible to get more of.
Conversely, the opposite is true. If your project is smaller, you’ll have extra yarn. (Though personally we can’t see the problem with having extra yarn and building a stash–this is how granny square afghans are born!)
Your project might not look right
Not only will it be the wrong size, but it could have a slightly distorted, stretched out shape. This usually happens when the number of stitches across four inches is very close, but the number of rows high across four inches is off.
How to check gauge
It’s commonly recommended to make a 4 inch by 4 inch swatch of the stitch you’ll be using (or as recommended by your pattern) but it’s easier to make a slightly larger than 4 inch by 4 inch swatch. This way you can measure a four by four inch area in the center, which gives a more accurate stitch and row count. (It’s also less tempting to scrunch up or stretch out your swatch to just “make it work.”)
How to fix it
If your gauge is off, there are two things you can do to adjust:
Adjust your tension
The first is changing your tension, or how loosely/tightly you make your stitches. This might sound easy, but if you’re working on a long project, it can be difficult to remember to keep this tension throughout. (It feels like trying to change muscle memory.)
Change your hook or needle size
If you have too many stitches, go up a hook/needle size to increase the size of your stitch (and decrease the amount of stitches per inch).
If you don’t have enough stitches, go down a hook/needle size to decrease the size of your stitch (and increase the amount of stitches per inch).