Gauge describes the size of a stitch. This size depends on: the yarn, the needle size, and the knitter. Typical knitting gauges range from 2 to 8 stitches per inch. Large needles make large loops, taking fewer stitches to fill an inch. Small needles make small loops, taking more stitches to fill an inch. When following a pattern, you must match to pattern's gauge for a predictable result.

When following a pattern it is critical to match the pattern's gauge. A pattern specifies its gauge as a number of stitches in 4 inches, for example 15 stitches in 4 inches. A pattern also tells you the stitch used to determine gauge. Typically this stitch is Stockinette Stitch. However, if the pattern is worked in a special stitch pattern such as cables, the stitch pattern is often used to determine gauge. If the pattern does not tell you, assume it's Stockinette Stitch.

With the yarn you intend to use for the project, cast on approximately 4 inches worth of stitches. How many stitches is this? Look at the pattern's gauge, if the gauge is 14 stitches in 4 inches then cast on 14 stitches. What size needle should you use? To start, use the size recommended by the pattern.

In the specified stitch pattern -- if not specified, use stockinette stitch -- work until the gauge swatch is approximately 4 inches high, finishing with a right side row. You're now ready to measure your swatch.

A More Accurate Gauge Swatch
For a slightly more accurate gauge swatch, add garter stitch borders to the swatch. Here's how:

* Add 6 more stitches to the swatch. These extra stitches are used to create the side garter stitch borders -- 3 stitches per side.
* Knit the first and last 4 rows of the swatch
* Knit the first and last 3 stitches of every row

Lay your gauge swatch on a flat surface (its okay to leave the gauge swatch on your needles). You may find it helpful to pin the swatch down so that it lays flat, just be careful not to artificially stretch the knitting.

Measure the width of your swatch:

* If the width of your swatch is 4 inches then you've matched the pattern's gauge and are ready to start.
* If the width of your swatch is not equal to 4 inches, you'll need to adjust your gauge.

To adjust your gauge to match a pattern's gauge, change your needle size.

* If your gauge swatch is less than 4 inches, you have too MANY stitches per inch. Your stitches are too small. You need to make your stitches bigger. To make bigger stitches, go up a needle size.
* If your gauge swatch is more than 4 inches, you have too FEW stitches per inch. Your stitches are too big. You need to make your stitches smaller. To make smaller stitches, go down a needle size.

Continue with your original gauge swatch. On the next wrong side row, knit all stitches using the new needle size. Continue working in the required pattern stitch for another 4 inches. Measure your new gauge and adjust accordingly.