The size of a cowl can vary widely depending on factors such as the design, the intended use, and personal preference. However, as a general guideline, most cowls range in circumference from approximately 20 to 30 inches (50 to 76 cm), and in height from approximately 6 to 12 inches (15 to 30 cm). Of course, these measurements are just averages, and you can adjust the size of your cowl depending on your needs and preferences. For example, if you want a cowl that can be worn loosely around your neck, you might choose to make it larger in circumference. Similarly, if you prefer a snugger fit, you might opt for a smaller circumference or a taller cowl that can be pulled up over your nose and mouth for added warmth. Ultimately, the size of your cowl will depend on your individual style and needs.