What is the diameter of hair measurements?

• A. Small, Medium, Large
• B. Thin, Medium, Thick
• C. Narrow, Regular, Wide
• D. Fine, Coarse, Medium

Answer: (B)

Diameter of hair refers to how thick each strand is. In practice, you describe that thickness with terms that clearly convey a range from thinner to thicker strands: thin, medium, thick. This trio is intuitive and directly communicates the variation in strand size, which helps you decide on appropriate techniques and products. The other options use terms that aren’t the standard way stylists categorize hair thickness, or mix descriptors in a less conventional way. While fine and coarse are common ways to talk about hair, the phrasing thin, medium, thick is the wording you’ll most often see for diameter, mapping cleanly to the idea of fine (thin) through to coarse (thick).