What is my BMI?

Use our body mass index (BMI) calculator to give you an idea of whether you're underweight, overweight or a healthy weight for your height. Being a healthy weight can be a challenge, but the benefits are huge.

What is my BMI?

One way of working out whether you're a healthy weight is to calculate your BMI. To use this BMI calculator, enter your weight (kg) and height (cm), and your BMI will be calculated for you. It is used as a tool to help identify people who may need extra support and weight management. 

Enter your height and weight

What does your BMI mean?

Underweight = <18.5

  • This result means that you may be underweight. Being underweight can be associated with a range of health issues. If you're concerned about your weight, we recommend discussing your result with your GP, practice nurse or dietitian.

Normal weight = 18.5–24.9

  • This result means that you are a healthy body weight which is generally good for your health. Keep up the great work!

Overweight = 25–29.9

  • This result means that you may be overweight. Carrying extra weight is associated with a range of health concerns, including being at an increased risk of heart disease. If you're concerned about your weight, we recommend discussing your result with your GP, practice nurse or dietitian.

Obesity = BMI of 30 or greater

  • This result means that you may be obese. Obesity is associated with a range of health concerns, including being at an increased risk of heart disease. If you're concerned about your weight, we recommend discussing your result with your GP, practice nurse or dietitian.

How accurate is BMI?

Although BMI is not a perfect measure, it is generally agreed to be the most useful and valid for adults (18 years and over). However there are limitations. For instance:

  • It is less accurate as an indicator of overweight in adults with higher than normal levels of lean body tissue (muscle mass). This is because muscle weighs more than fat and the BMI does not take this into consideration.
  • It is less accurate as an indicator of overweight in ethnic groups with smaller body stature (i.e. Asian ethnic groups).

Along with BMI, measuring your waist circumference can help you to determine whether you are carrying excess weight around your middle and your risk of heart disease and type 2 diabetes.

Because children are still growing, the BMI calculator on this website is just for adults and should not be used for children. If you're under 18 years of age, seek advice from your GP about what a healthy weight is.

Pregnancy also affects BMI, but a woman’s weight gain during pregnancy is necessary for a healthy baby. If you're pregnant, seek advice from your GP or midwife on healthy weight gain during pregnancy.

For people above a healthy weight, losing five to ten percent of your weight can lower blood pressure, improve cholesterol levels, and help protect against diabetes and cancer.

Losing weight and keeping it off is about eating wellmoving more, and instilling lifelong healthy habits.

How do I lose weight?