A person’s level of overweight can be calculated using the Body Mass Index (BMI).
The BMI expresses the relationship between weight and height in a single figure.

For example:
Height: 1.70 metres (5.5 ft.)
Weight: 130 kilos (287 lb)

Formula:
Height squared: 1.70 m x 1.70 m = 2.89 (5.5 ft. x 5.5 ft = 30.25)
Weight divided by height squared: 130/2.89 = BMI 44.9 (287/30.25 = BMI 9.5)