The differences between thick and thin hair have been widely studied by scientists and hair dressers alike. In understanding the differences between thick and thin hair, it is useful to learn about hair density, thickness measurements, the way thick and thin hair respond differently to different cuts, and general trends that determine hair thickness.
"Hair density" refers to the number of hairs on the head. Density is the main difference between thick and thin hair. Thick hair has a higher density, thin hair's density is lower. Density is determined according to the number of hairs on one square inch of the head. On average, humans have about 2,200 hairs per square inch. Those with more than 2,200 strands have thicker hair, those with less have thinner hair. Since each hair grows from a pocket-like hole called a follicle, people with thicker hair will also have more follicles than those with thin hair.
A simple technique can be used to determine the difference between thick and thin hair in terms of measurement. If hair is long enough to be gathered into a ponytail, the circumference of the ponytail will indicate thickness. Thin hair has a circumference of 2 inches or less. Thick hair measures 4 or more inches around. Measurements in between are considered "normal," not notably thick or thin.
Another difference between thick and thin hair is the way the hair is affected by cut. Thick hair works best with a layered cut. Thin hair usually works best with a blunter cut, where all hairs fall at the same length. Thin hair usually takes well to curling and styles that add volume. Thick hair often looks best with straighter styles, as too much volume tends to be a problem for people with thick hair.
Color and Ethinicity
Though not a steadfast rule, color and ethinicity are two more differences between thick and thin hair. Thick hair is characteristic of blondes and brunettes. Thin hair is more characteristic of redheads. In terms of ethnicity, Caucasians tend to have thicker hair, whereas Far East Asians tend to have thin hair. Though color and ethnicity are interesting ways to classify hair types, measurement is the only way truly determine whether you have thick or thin hair.