The average weight of a 12-year-old boy is 90 pounds, according to the Centers for Disease Control. Boys in the top 10% of the population weigh 120 pounds or more at this age, while those in the bottom 10% weigh 70 pounds or less.
The CDC also provides information on average height for boys. The height ranges for 12-year-olds are not as wide as the weight ranges. The average height is 59 inches (4 feet and 11 inches). Boys in the top 10% of the population are 5 feet 2 inches or taller. Boys in the bottom 10% of this age group stand at 4 feet, 7 inches or below.
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