BMI is your weight (in kilograms) over your height squared (in centimeters). Let’s calculate, however, using pounds and inches.

For instance, the BMI of a person who is 5’3" and weighs 125 lbs is calculated as follows:

```
1. Multiply the weight in pounds by 0.45 (the metric conversion factor)
125 X 0.45 = 56.25 kg
2. Multiply the height in inches by 0.025 (the metric conversion factor)
63 X 0.025 = 1.575 m
3. Square the answer from step 2
1.575 X 1.575 = 2.480625
4.Divide the answer from step 1 by the answer from step 3
56.25 : 2.480625 = 22.7
```

The BMI for a person who is 5’3" and weighs 125 lbs is 22.7 or practically, 23.

A healthy BMI ranges between 19 and 25.