Crochet a gauge swatch to keep stitches consistent and the size of your design on track. When you work crochet the gauge swatch, work the stitches according to the instructions in the pattern. Crochet patterns almost always recommend a gauge for you to follow. Look for it at the beginning of the pattern instructions.
The pattern designer determines the gauge by taking into account the recommended yarn and hook size, the type of stitches used in the pattern, and the desired result. Although garment patterns usually mention both a stitch and a row gauge, the stitch gauge is the most important one to match. The stitch gauge determines the width of each piece of the design, which, when you sew the front and back together, adds up to the finished bust/chest measurement.
A simple pattern that uses just one stitch, like a single crochet stitch, states the gauge as a certain number of stitches and rows per a given number of inches. However, some patterns have a set of several different stitches that repeats across the row. In this case, the pattern states the gauge as one entire stitch repeat per a given number of inches.
Crocheters tend to crochet tighter at the beginning and end of rows than in the body of their work. So if the gauge calls for 7 stitches = 2 inches and 8 rows = 2 inches, make your swatch at least 4 inches square. That way, you can measure in the center of the swatch and get an accurate measurement of your normal pace. If you’re working a gauge that has a repeated set of stitches, you may need to make it bigger than 4 inches square.