Greying of the human hair: a worldwide survey, revisiting the '50' rule of thumb

Br J Dermatol. 2012 Oct;167(4):865-73. doi: 10.1111/j.1365-2133.2012.11095.x.


Background: While numerous papers have reported on the biological mechanisms of human hair pigmentation and greying, epidemiological descriptions of both natural hair colour and the greying process, worldwide, remain scarce.

Objectives: To assess hair colour and greying in a large world sample of human subjects, and to revisit the validity of the 50/50/50 rule of thumb, which states that 'at age 50 years, 50% of the population has at least 50% grey hair'.

Methods: The natural hair colour of 4192 healthy male and female volunteers was assessed using a sensorial expert evaluation through the comparison of each volunteer's hair with standard swatches. Hair colour was studied according to age, gender and ethnic or geographical origin.

Results: Overall we observed that between 45 and 65 years of age, 74% of people were affected by grey hair with a mean intensity of 27%. Men harboured significantly more grey hair than women. Both age at onset and rate of greying with age appeared to be clearly linked to ethnic/geographical origin. Subjects of Asian and African descent showed less grey hair than those of caucasian origin, at comparable ages, confirming previously reported data.

Conclusions: Calculating the percentage of people showing at least 50% grey hair coverage at age 50 years leads to a global range of 6-23%, according to ethnic/geographical origin and natural hair colour: well below that expressed by the '50' rule of thumb.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Aged
  • Aging / physiology
  • Asian People
  • Black People
  • Female
  • Hair Color / genetics*
  • Hair Color / physiology
  • Humans
  • Male
  • Middle Aged
  • Pigmentation / genetics*
  • Pigmentation / physiology
  • Statistics, Nonparametric
  • White People