Hairs are grouped in the form of follicular units.
We have approximately 90 000-150 000 hairs on the scalp. This number varies from person to person depending on density.
Humans have approximately 120 to 260 hairs per cm2 approximately (60-120 follicles per cm2) with a total of 90 000-150 000 on all the head.
No. Since each follicular unit can have 3 or 4 hairs.
For us, 2400 follicular units would correspond to approximately 4800-6000 hairs, depending mainly on the number of follicular units of 3 and 4 hairs in the donor area of the patient.
In this case, 4800 hairs would refer to a patient with low follicular density, while 6000 hairs would refer to a patient with average follicular density.
A patient with 60 follicles/cm2 has approximately = 120-140 hairs/cm2.
Another patient with 90 follicles/cm2 has approximately = 180-200 hairs/cm2.
That is why, when we go down the street, we can see people with a greater hair volume (higher density) and others with less voluminous hair (lesser density).
There can be variations according to the ethnic background:
Hair does not grow indefinitely, but has a cyclic growth, which is called the hair follicle cycle.
Every follicle has its own cycle, independent of those around.
|Growth depending on type of hair||Duration of the Anagen phase|
|Hair||3-5 years (1095-1825 days)|
|Beard||1 year (365 days)|
|Body hair||13-15 weeks (91-105 days)|
|Eyebrows||1 month (30 days)|
|Moustache||4-14 weeks (28-98 days)|
Every 2 days and 9½ hours, any hair grows at least one millimetre more.
In men, growth is approximately 1 cm per month.
In women, growth is approximately 1 to 1.5 cm per month.