Gauge is an extremely important part knitting, but it's also often the most misunderstood! Simply put, "gauge" means "stitches per inch." In other words, your gauge is how tightly or loosely you knit.
WHY GAUGE IS IMPORTANT
If you don't get the same number of stitches per inch as your pattern, that means your stitches will either be too big or too small, which means your whole project will be too big or too small, too!
Sometimes gauge isn't important, like when you're making things like scarves or blankets. No one will likely mind if those come out a little larger or smaller than what the pattern said. But even with projects like those, it's important to remember that getting a different gauge will mean you will use more or less yarn than what the pattern said was needed (looser stitches means less yarn, generally).
HOW TO CHECK YOUR GAUGE
To measure your gauge, hold a tape measure or gauge measurer up to your stitches and count how many stitches fit within one inch.
We also recommend counting how many stitches fit within 4 inches, then dividing that number by 4 to find the number of stitches per 1 inch.
Sometimes it can look like you're getting 5 stitches per inch, but then when you count how many stitches fit in 4 inches it's actually 21 (which makes your gauge 5.25 stitches per inch instead of 5).
Make sure to measure your gauge in a few different places (and if your gauge varies, average all the different numbers you count).
MAKING GAUGE SWATCHES
The best way to check your gauge is to knit a gauge swatch! You should knit your swatch before starting your project. Even though knitting gauge swatches may be tedious, but it's definitely less tedious than remaking an entire project because it came out the wrong size!
To knit a gauge swatch in stockinette stitch with a garter stitch border, you can follow our free pattern which includes instructions for knitting swatches in 15 different gauges and gives you a suggested needle size for each gauge.
MY GAUGE IS WRONG, WHAT SHOULD I DO?
If your stitches are too tight: knit a swatch using a needle one size larger than the last one you used and see if your stitches loosen up to the gauge that you need.
If your stitches are too loose: knit a swatch using a needle one size smaller than the last one you used and see if your stitches tighten up to the gauge that you need.
The most important part of understanding gauge is that the needle size doesn't matter. Most patterns will tell you what needle size they used, but that doesn't mean you should use the same one. Everyone knits differently, and even if you know you're an average knitter (as opposed to a loose or tight knitter), the person who wrote the pattern you're following might not have been.
If you have the right number of stitches per inch, but you don't have the right number of rows per inch: first, don't worry too much! Row gauge is not usually as important as stitch gauge, since most patterns will tell you to knit a certain number of inches instead of a certain number of rows. If your row gauge is important, try blocking your swatch and stretching it into the correct gauge.
YARN CHOICES & GAUGE
Just as with the needles you use, the yarn you use doesn't matter when it comes to gauge either. As long as you're getting the same gauge as your pattern, the yarn and needles you use will not affect the size of your finished project. However, your yarn and needle choices will affect how the fabric of your project will look and feel.
For instance, if a pattern tells you to get 5 stitches per inch, you can get that gauge with a bulky yarn, but your stitches will be very tight and the fabric will be stiff. On the other hand, if you use a fingering weight yarn to get 5 stitches per inch, your stitches will be very loose and the fabric will be open and have more of a drape. The needle size you use to get 5 stitches per inch could be the same for both yarns (an average knitter would usually get 5 stitches per inch on a US 7 / 4.5 mm needle), but sometimes the weight of the yarn affects how tightly or loosely you knit. You may need to use a US 7 / 4.5 mm needle to get 5 stitches per inch with a bulky yarn, and a US 8 / 5 mm needle to get 5 stitches per inch with a fingering weight yarn. Like we said above, your needle size doesn't matter. What's most important is that you use the needle that gets you the correct gauge, no matter the yarn.
Stitch patterns also affect gauge. Most gauge swatches are made in stockinette stitch, as most patterns use stockinette stitch as their main stitch pattern. You should always make your swatch in the stitch pattern that your pattern indicates (if it doesn't indicate which stitch pattern you should use it's usually safe to assume it means to make it in stockinette stitch).
TIPS ON MAKING SWATCHES
When making swatches, you should make them at least 4" x 4" so that you can measure the stitches in a few different places. If you're making your swatch in stockinette, add a border in another stitch so that the edges of the swatch don't curl. We encourage you to follow our free swatch pattern to make a stockinette swatch with a garter stitch border.