Standard weight charts indicate that an average 13-year-old female should weigh approximately 101 pounds. This is based on a calculation of a 13-year-old female who is 61.7 inches, or 5.1 feet, tall. Teenagers who are taller are likely to weigh more.
In contrast, a 13-year-old male should weigh on average 100 pounds, which is roughly based on the same height. It is in the 14th year that averages and standards begin to change. At age 14, a girl should weigh approximately 105 pounds and a 14-year-old boy 112 pounds. This would be if a 14-year-old boy was 64.5 inches tall, and a 14-year-old girl 62.5 inches tall.