If you are 4 foot 11 inches to 5 foot 1 inch tall, your weight is average proportionally to your height. For girls, figure 100 lbs at 5 foot tall and add 5 lbs per inch over 5 foot. For boys, figure 105 lbs at 5 foot and add 5 lbs for every inch over. Children tend to gain or lose weight as they grow up to reach and average weight for their heighth.