According to Baylor College of Medicine, girls typically stop growing taller between the ages of 18 and 20. However, their bones continue to grow in thickness and strength until their mid-20s.
There is no set age that determines when all girls stop growing, according to HealthGuidance.org. A girl stops growing when her growth plates close, which is likely determined genetically and is different for each individual. Most girls experience 95 percent of their adult height growth spurt by the age of 16. On average, girls gain between 6 and 7 inches during the five-year period that starts around age 10 or 11.