You know what gauge is and why matching a pattern's recommended gauge is important. But what are you supposed to do about it? Read on to come to grips with getting the correct gauge.
Relaxing with your knitting
Knitters all vary in the way that they hold needles and move yarn. This variation means that with the same yarn and needles, different knitters will knit to different gauges. One may create a fabric that's loose and see-through while another may make something that's practically bulletproof. It's important to recognize that matching the suggested gauge with the suggested needle size isn't a sign of a good knitter; it's only a sign of a knitter who happens to have similar tension to the person who made the pattern or packaged the yarn!
New knitters often ask whether they should change the way they hold the yarn or wrap it around their fingers or whether they should do something to snug up the yarn after each stitch. Hold the yarn and needles so that you're comfortable. As long as you're making the stitches correctly, don't try to correct your tension. Correcting your tension generally leads to overcorrection. So, anything you do to make your stitches tighter or looser will likely change when you relax and get going. The end result will likely be worse, not better, because some spots will be looser and some spots tighter.
Switching needles if your gauge is off
Okay, so maybe you're comfortable with your needles, and your gauge is more consistent, but it's consistently off. Your stitches are too big and you're getting 4 stitches per inch instead of 4.5. Big deal, you say. It's close enough, right? Wrong! Unlike horseshoes and slow dancing, close doesn't count in knitting. Here's why: Imagine a sweater front that's supposed to be knit at 4.5 stitches per inch. The directions say to cast on 90 stitches. The number of stitches on the needle, divided by the number of stitches per inch (or gauge) gives you the width of your knitting. Here's the filled-in equation:
90 stitches ÷ 4.5 stitches per inch = 20 inches
From this equation, you determine that the sweater is 20 inches across. A quick study of the accompanying schematic confirms that this is how wide the sweater should be in the size that you want.
But at a gauge of 4 stitches per inch, what happens? Put the new gauge into the equation as follows to find out:
90 stitches ÷ 4 stitches per inch = 22.5 inches
This math shows that the front of the sweater is 2.5 inches wider at the new gauge. That means the whole sweater will be 5 inches bigger around. That's more than a whole size bigger!
You have equally ugly problems if your knitting is tighter than the suggested tension. If your gauge is 5 stitches to the inch rather than 4.5 stitches, here's what happens:
90 stitches ÷ 5 stitches per inch = 18 inches
The front of this sweater is 2 inches narrower than your intended size; the whole sweater will be 4 inches smaller around. Depending on the intended fit of the sweater, you may not even be able to get it on! Everything, including the ribbing around the neck, will be too tight.
You may hear a knitter say, "I'll just follow the directions for the next smallest size." This compensation for a loose gauge can work if you're careful (very, very careful) in how you deal with the lengths of each piece, but you haven't really fixed the problem with your stitches that are too big. The fabric you're creating may simply not look right if your gauge isn't correct.
The real way to change the number of stitches that you knit in an inch is to change the needles that you're using. A needle with a smaller diameter means that you make smaller loops when you wrap the yarn, and therefore you get smaller stitches. Likewise, bigger needles make bigger stitches.