Gauge is the number of stitches per inch in a crocheted or knitted item. Almost all patterns will tell you what the gauge is. For items like placemats, scarves, some blankets or throws, gauge may not be important. Wearable items like socks, hats, gloves, and garments require you to pay close attention to the pattern’s gauge.
Are you on track? Usually gauge is measured in a four-inch block. Crochet or knit a four-inch by four-inch square using the recommended needle and yarn. This is your gauge swatch. Compare the number of stitches and rows to the gauge in the pattern. If it matches, you can continue. But what if your swatch does not match the pattern’s gauge?
If your swatch is too small, use larger needles and try again until you get the correct gauge. If that does not work, try using a thicker yarn. For example go from sport weight to worsted weight (or a 3 to a 4.) Another trick is to make your stitches looser.
If your gauge swatch is too large, tighten up your stitches and use smaller needles. If this does not work, try a lighter weight yarn.
If the pattern is worked in the round instead of in rows, create your gauge swatch in the round. Most people knit or crochet tighter when working in the round. You might find that your gauge is correct when working in rows, but you are off when working in the round. This can save you a lot of time later on.
Why is gauge important? If you want your garments to come out as expected and true to size, paying attention to gauge will give you consistent results every time.