The CDC (Centers for Disease Control and Prevention) indicates how much a person should weigh varies based on individual factors such as current height and weight. The calculation used to indicate whether a person is over- or underweight is the body mass index (BMI).
The CDC reports the formula used to configure a person's BMI is [weight in pounds/(height in inches x height in inches)] x 703
Underweight = BMI < 18.5
Normal weight = BMI 18.5-24.9
Overweight = BMI 25-29.9
Obesity = BMI 30 or above
BMI does not factor in increased muscularity, however, which can make the formula inefficient for some.