Calculate your BMI
What is BMI?
BMI stands for Body Mass Index. It's calculated by dividing your weight in kg by your height in metres squared. It's a reliable indicator of whether you're at a healthy weight. BMI results are divided into four categories: underweight, healthy weight, overweight and obese.
If your BMI is below 18.5, you're classified as underweight. Healthy weight is in the range 18.5 to 24.5; overweight is from 25 to 29.5, and if your BMI is 30 or over, you're obese. To calculate your BMI, type your height and weight into the boxes and click 'calculate'.
Why is a healthy BMI important?
A healthy BMI can help to reduce your chances of serious medical conditions such as high blood pressure and cardiovascular disease. Having a healthy BMI will also give you higher energy levels, make you look younger and live longer. If you exercise regularly and eat a healthy diet, it is likely your BMI will fall into this healthy category. Being overweight or underweight increases your risks of developing serious health conditions.
Calculate your BMI
BMI Ranges
- Under weight:
- 18.5 or under
- Healthy weight:
- 18.5 to 24.9
- Overweight:
- 25 to 29.9
- Obese:
- 30 or over
Your Body Mass Index, or BMI, is within the underweight range of below 18.5.
If you have a low BMI, below 18.5, you're at risk of many conditions including malnutrition, osteoporosis, anaemia, irregular periods, infertility and a suppressed immune system, putting you at increased risk from other illnesses. Visit your GP if your BMI is this low.
Congratulations - your BMI is in the healthy weight range, between 18.5 and 24.9. It's important to eat a healthy balanced diet - see our 'Healthy eating' section for advice and inspiration.
Your Body Mass Index, or BMI, is within the overweight range of 25-29.9.
If you have a high BMI, between 25 and 29.9, you are overweight and you're at greater risk of suffering health problems such as diabetes, heart disease and certain cancers. Losing enough weight to take your result into the healthy BMI range is a sensible choice.
See our Diets and weight loss ideas for inspiration and advice 
Your Body Mass Index, or BMI, is within the obese range of 30 or over.
If your BMI is 30 or over, you are obese and you're at much greater risk of suffering health problems such as diabetes, heart disease and certain cancers. Losing enough weight to take your result into the healthy BMI range is a sensible choice.
See our Diets and weight loss ideas for inspiration and advice
