We all know that we're supposed to knit gauge swatches and do whatever we have to do to make sure we're getting the same number of stitches per inch as the pattern calls for. If you don't take the time to check your gauge and yours happens to be way off from what the pattern suggested, you'll end up with a project that's much bigger -- or smaller -- than you intended.
But it's not always easy to figure out what to do to alter your gauge.
If you've knit a swatch with the needles specified and it's not right, what can you do?
Go Up a Needle Size
A bigger needle is what you need if you're getting more stitches to the inch than the pattern calls for. (Which makes sense, because a bigger needle makes bigger stitches, so there will be fewer of them per inch.)
Go Down a Needle Size
On the other hand, if you're getting fewer stitches per inch than you are supposed to be, going down a needle size should get you more stitches per inch.
Change the Type of Needle
Even though needle size is supposed to be consistent, different needles are not always exactly the same size, and the way you knit might be altered a little bit when you use needles of different materials.
Using a different kind of needle is said to be particularly helpful if you're getting stitch gauge but not row gauge. Row gauge is not always important, of course, but it can be if, say, you're knitting a garment sideways.
Change the Way You Knit
In the picture shown here, the bottom blue stripe on the top swatch was knit English and all the rest was worked continental.
I got 4 stitches per inch on a size 8 US (5 mm) knitting needle working English style, but I had to go down to a size 6 US (4 mm) to get the same gauge working continental style.
It's great to know different styles for a lot of reasons, but I switched from my normal form for this particular project because of a repetitive strain issue.
Make Sure You're Happy
If you have to alter your needle size, type, or style of knitting in order to get to the gauge you need, make sure you stop and look at the swatch before you cast on. Are you happy with the way the fabric looks and feels? Sometimes getting to gauge with a much smaller needle will make the fabric too stiff, and you'd be better off choosing a different yarn or pattern rather than moving ahead with the project if the finished garment won't make you happy.