Question: what is the average height for a 1 1/2 year old boy?
Answer: At fifteen months, the average girl weighs about 23 pounds (10.5 kg) and is almost 30.5 inches (77 cm) tall; the average boy weighs about 24.5 pounds (11 kg) and is 31 inches (78 cm) tall. Over the next three months, they'll each gain approximately 1 1⁄2 pounds (0.7 kg) and grow about an inch (2.5 cm).