Hair Growth in 12-Year-Old Girls: Average Rate & Factors

The rate of hair growth is pretty similar across ages and genders. On average, head hair grows about 0.5 inches (1.25 cm) per month, or around 6 inches (15 cm) per year.

So, for a 12-year-old girl, you can expect her hair to grow at roughly that rate. Keep in mind that individual growth rates can vary depending on genetics, overall health, and nutrition.