The number of yards of yarn needed to make a cowl can vary widely depending on factors such as the size of the cowl, the stitch pattern used, the thickness of the yarn, and the desired drape. As a general guideline, a typical cowl made with worsted weight yarn and a basic stitch pattern might require between 150 to 300 yards of yarn. However, a more complex stitch pattern or a larger cowl may require more yarn.  It's always a good idea to check the pattern you're using for specific yarn requirements, as the designer will usually include this information.