QuestionWhen does the average girl stop getting taller?
Please understand that you asked about the average girl. Very few girls are actually average. It is only when you combine all girls' growth, both those grew later and those who grew earlier, that you can arrive at an average number.
All children grow continuously, but about two years after the first signs of puberty, a girl will go through a rapid growth spurt where she will increase in height at twice the rate she once grew. The average start of puberty in girls is at age 10 1/2; hence, the average age to start the growth spurt is around 12 (it usually happens about six months before menarche -- your first period). Typically it takes two years to reach your final height. Therefore, the average girl reaches her full adult height at the age of 14 1/2.
Now, this doesn't mean you are done growing. You will still spend a few years filling out and your brain will continue to develop for several more years.