Hair typically grows at an average rate of about 1 centimeter (0.5 to 1.7 cm) per month, which translates to roughly 6 inches (15 cm) per year, though this can vary depending on factors such as age, genetics, sex, and ethnicity
. Hair growth occurs in cycles with four main phases:
- Anagen (growth phase): Lasts 2 to 8 years (commonly 3 to 5 years), during which hair actively grows about half an inch per month. The length of this phase determines how long hair can grow
- Catagen (transition phase): Lasts about 10 days to 4-6 weeks, where hair growth stops and the follicle shrinks
- Telogen (resting phase): Lasts around 2 to 3 months, when hair is dormant and eventually sheds
- Exogen (shedding phase): Hair falls out, making way for new growth
Because hair follicles are in different phases at any given time, hair grows continuously, but the visible regrowth after hair loss depends on how much hair was lost and the cause.
How long does it take for hair to grow back?
- If hair is completely shaved or lost, it generally takes about 3 to 6 months to see noticeable regrowth, with hair initially appearing as soft fuzz
- For hair to return to a previous length, such as shoulder-length hair cut short, it can take several years , since hair grows about 12 cm (around 5 inches) per year on average
- After chemotherapy, hair may start regrowing within 2 to 3 weeks , with thicker hair appearing after about a month. Full regrowth to a styleable length can take 12 months or more , and sometimes several years for hair to fully recover in texture and thickness
Factors influencing hair regrowth time:
- Age (growth slows with age)
- Genetics and ethnicity
- Hair thickness (thicker hair tends to grow faster)
- Cause of hair loss (e.g., chemotherapy, telogen effluvium, hormonal changes)
- Overall health and nutrition
In summary, hair grows about 1 cm per month on average, so regrowing hair after loss or cutting depends on the length desired and individual factors, with initial regrowth visible in a few weeks to months and full length restoration potentially taking years
