Complex sentence: She stood six feet tall (1.83m) on her 12th birthday and her final adult height, which she reached by her 17th birthday, was just over 6' 5 (1.96 m).
Split into simpler sentences: She stood six feet tall (1.83m) on her 12th birthday. Her final adult height, which she reached by her 17th birthday, was just over 6' 5 (1.96 m).