Scalp hair tends to grow at a fairly steady rate for an adult. The rate may show differ between individuals.



Growth per Day

Growth in 30 Days

Vogt et al

0.35 mm

10.5 mm

Omega Laboratories

0.423 mm

12.7 mm


An individual’s hair growth can be estimated by shaving a small area then measuring the length of hairs left to grow for a period of time.


individual’s hair growth rate =

= (total length in mm) / (number of days)


If a hair sample is submitted:


number of days represented by the sample =

= (length of the hair in mm) / (growth per day in mm)

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