Take your weight in kilograms (kg) and divide it by 
your height in metresThe Body Mass Index (BMI) enables you to tell how healthy your weight is. You can use BMI to find out if you’re healthy for your height.
If you know your height and weight, you can work out which weight range you’re in using the simple steps below.
Take your weight in kilograms (kg) and divide it by your height in metres
Then divide the answer by your height in metres again.
For example:
If you weigh 70kg, and you’re 1.75m tall, your BMI is 22.9
70 / 1.75 = 40 and 40 / 1.75 = 22.9
If your BMI is below 18.5 you’re underweight
If your BMI is between 18.6 to 24.9 you’re a healthy weight
If your BMI is between 25 to 29.9 you’re overweight
If your BMI is 30 and over you’re obese