Hair Density View hair transplant photos organized by each patient’s hair density (measured by hairs/mm2). 1.2 1.4 1.5 1.6 1.7 1.8 1.9 2 2.0 2.1 2.1 hairs/mm2 2.2 2.2 hairs/mm2 2.3 2.3 hairs/mm2 2.4 2.5 2.6 2.7 2.8 2.9 2.9 hairs per follicular unit 2.25 2.35 3.0 ▲ Top of Page By: Dr. Robert M. Bernstein Updated: 2019-11-15 | Published: 2013-01-07