Deciding Which Yarn to Use - as part of the expert series by GeoBeats. The first thing you need to do, when determining which yarn is going to work for your project, is to look at the pattern and see what the gauge calls for. A pattern that has a gauge of 20 stitches to 4 inches means that you need a yarn that is going to have 5 stitches to the inch. And the only way you can determine that is by looking at the ball band on the yarn which, has a lot of different information on it. It will tell you if the yarn is machine washable, it will tell you if the yarn can go in a dryer, it will tell you what size needles you need to use and it will have a small box on it that will tell you how many stitches and how many rows fit inside 4 inches. So, this yarn actually has 15 stitches and 21 rows that fit inside 4 inche,s which, means it has a gauge of about 3-1/2 to the inch. So, your pattern, if it says that you need 3-1/2 to the inches as your gauge, that means this is the yarn that is going to work for you. The only way that you can determine if the pattern is going to work, is to look at the ball band and then to cast on, let’s say, 15 stitches, and work for 21 rows and measure it. If after 15 stitches and 21 rows, you have a fabric that is 4 inches by 4 inches, you know that this yarn is going to work for the pattern that you are using.