What is the average weight for 16 year old girl who is 5 feet 5 inches?

Rather than the average weight if we look at the "normal" weight for someone who is 5 ft tall it falls between 95 lbs and 125 lbs. This number is calculated based on the typical accepted "normal" range for BMI (body mass index) values.

The well regarded BMI range for a normal weight is between 18.5 and 25, which the 95 - 125 lbs range above directly corresponds to.