Perhaps the single most important concept in the knitting world, gauge refers to the size of each stitch. Knitting is a very personal art, with some of us knitting more loosely than others, and pattern writers explain their own sizing by giving us their gauge measurements. To do this in a way that we can easily use, pattern writers will create a square or rectangle of knitting, called a swatch that uses the pattern stitch/es, and then measure it for both width and length. We then create our own swatch using the same size needles recommended in the pattern, and then measure it. When we compare the measurements, we can then see if our knitting matches the gauge of a pattern. Consider this: if our knit stitches are looser than those of the pattern writers, each stitch will be bigger; if we knit more tightly, each stitch will be smaller. As each project is made up of multiple stitches, this means that a small difference in gauge will multiply out to change the size of the finished piece, sometimes dramatically.
As an example how a difference in gauge affects size, let’s say that the given gauge states “22 stitches and 28 rows = 4 inches in charted pattern.” (Most often, a pattern will describe gauge in terms of multiple groups of stitches.) Elsewhere in the essential information, usually just above the gauge guide, we see that the pattern suggests a needle size of 6. We knit up a gauge swatch using the same size needles and find that we are getting 20 stitches in four inches. A little math will demonstrate that the given gauge gives us 5.5 stitches per inch, whereas we are getting 5 stitches per inch. This doesn’t seem like that much of a difference, but if we’re trying to make a sweater with a chest measurement of forty inches, the difference in gauge will result in a sweater that’s forty-four inches around, which will make the sweater two sizes too large!
The easiest way to compare gauge is to create a swatch that uses the same number of stitches as the stated gauge, perhaps with a three stitch border on each side. Cast on, knit a few rows for a border, than knit the same number of rows as listed before again bordering the swatch. Then measure the section between the borders, and compare the numbers. It the gauges match, begin the pattern. If the swatch is too small, create another one using larger needles. If the swatch is too large, go down a needle size. Experiment until the gauges match.
Suppose we experiment with gauge swatches and still can’t match the gauge? Another way to use the information is to then figure out what sizes we will create if we use a different set of size instructions. Using the above example, we found that our gauge will create a sweater that’s forty-four inches rather than the intended forty if we cast on the number of stitches listed. If we multiple our gauge of five inches by the forty that we want, we end up needing two hundred stitches around. Is there a listed ‘size’ that uses this number of stitches for the main sweater body in the round? If the pattern is written in pieces, is there a “size” that uses half this number, or one hundred stitches, for the main body? That would be the “size” to use!
The type of pattern will determine whether we should change needle sizes or use a different set of numbers. Socks are usually knit at a tighter gauge, and going up a needle size might create socks that are too loosely knit to withstand the wear of a shoe; going down a needle size might make the process too tight for enjoyable knitting. In such cases, we use a smaller or larger ‘size’ if we can, and realize that unfortunately certain patterns simply don’t work for large or small feet without extensive alterations. Hat patterns don’t always list multiple sizes, and so changing the needle dimensions is obviously the way to go.