according to Kaswell 15µm - 110µm: according to Randebrook 40µm - 120µm µm
||Human Homo sapiens
||Robbins, Clarence R. Morphological and macromolecular structure, pp.1-62, chapter 1 in the book Chemical and physical behavior of human hair / Clarence R. Robbins.-2nd ed (2002) p.1 3rd paragraph
|| Kaswell, E.R. "Textile Fibers Yarns and Fabrics," p. 52, Reinhold, New York (1953)  Randebrook, R.J. J. Journal of the Society of Cosmetic Chemists, Vol. 15, No. 12, 691-706 (1964)
||P.1 3rd paragraph: "Kaswell [primary source 2] has suggested that the diameter of human hair fibers varies from 15 to 110 microns. Randebrook [primary source 3] provides a somewhat larger estimate, of 40 to 120 microns. See Figure 1-2, which illustrates the range in fiber diameters and cross-sectional shapes of hairs from five different Caucasian adults. For a more complete discussion of hair fiber diameter, see Chapter 8 and the review by Bogaty [ref 4] and the references therein."