There is no single answer to this question because there are many factors that can affect beard growth, including genetics, hormones, and age. However, there are a few things that may help promote faster beard growth in teenagers: eating a healthy diet with plenty of protein and vitamins (such as biotin and vitamin B5), exercising regularly, managing stress levels, and getting enough sleep. Additionally, using products specifically designed to encourage beard growth (like minoxidil) may also be helpful.
A full beard takes 2 to 4 months to grow, as facial hair grows between 0.2 and 0.5mm every 24 hours. Eating a healthy diet with plenty of protein and vitamins, exercising regularly, managing stress levels, and getting enough sleep may help. Using products specifically designed to encourage beard growth (like minoxidil) may also be helpful.
How Fast Does Facial Hair Grow Teenager?
Understanding facial hair growth can help you maximize your beard potential. A full beard takes 2 to 4 months to grow, as facial hair grows between 0.2 and 0.5mm every 24 hours. It works out to between one third and one half an inch per month. 
Can A 14 Year Old Grow Facial Hair?
One of the last changes of puberty is getting hair on your face. Boys begin to notice hair on their face around the age of 15 or 16. Changes of puberty can vary a lot. How fast the changes occur can vary. 
Do You Start Growing Facial Hair At 16?
During puberty, the first facial hair to appear tends to grow at the corners of the upper lip. It forms a moustache over the entire upper lip. The upper part of the cheeks and the area under the lower lip have hair. 
Frank Harmenstein is the lead editor of the grooming website Cut Throat Straight Razor, and has over 15 years of experience in the industry. He’s personally tested and reviewed over 200 different straight razors, and has written countless articles on the subject.