BMI calculator

How to calculate BMI

Our body mass index (BMI) calculator is a simple way to find out whether you’re a healthy weight for your height. Being a healthy weight is one of the most important things you can do to reduce your risk of cancer.

What is my BMI?

Use our BMI healthy weight calculator to see if you’re within the healthy range. Your ideal body weight is as low as possible within the healthy range.

For most adults, using a BMI calculator is a good way of checking if you have an ideal weight. However, a BMI test may be a less reliable indicator of body fatness for some groups of people, including:

  • athletes
  • some ethnic groups
  • older people
  • pregnant women
  • those less than 1.5m/5ft tall

Enter your height in:
Enter your weight in:

What should I do if I’m worried about my BMI?

If our BMI calculator finds that you don’t have a healthy weight, we recommend you talk to your GP before making any really big changes to your diet or the amount of exercise you do.

However, don’t let that stop you making small changes today. If the BMI calculator finds you are more than the ideal weight, losing just a few pounds is a great start, and can improve your health and lower your risk of cancer and other diseases. If your BMI indicates you are less than the ideal weight, gaining some weight could benefit your health.