Your measurements
Your result
BMI is a general guide for most adults aged 18–64. It does not directly measure body fat, so it can be less accurate for very muscular people, pregnant women, older adults, and some ethnic groups (the NHS suggests people of South Asian, Chinese, and some other backgrounds may face health risks at a lower BMI). For a personalised assessment, speak to your GP. This tool is for general information only and does not constitute medical advice.
Explanation
What is BMI?
BMI, or Body Mass Index, is a simple calculation that uses your height and weight to give an indication of whether you are a healthy weight.
It is worked out by dividing your weight in kilograms by your height in metres squared.
Because it is quick and requires no special equipment, it is widely used by the NHS and healthcare professionals as a starting point for discussions about weight and health.
Understanding your result
For most adults, the NHS uses the following ranges: a BMI below 18.5 is considered underweight, between 18.5 and 24.9 is a healthy weight, between 25 and 29.9 is overweight, and 30 or above is in the obese range.
These categories give a general indication of whether your weight could be affecting your health.
The limitations of BMI
BMI is a useful guide, but it is not a perfect measure and does not tell the whole story.
Because it only uses height and weight, it cannot distinguish between fat and muscle.
This means very muscular people, such as athletes, may have a high BMI while having very little body fat.
It is also not suitable for use during pregnancy, and may be less reliable for older adults, children, and people from certain ethnic backgrounds.
The NHS notes, for example, that adults of South Asian, Chinese, and some other origins may have a higher risk of health problems at a lower BMI, and so different thresholds may apply.
What to do next
A BMI result outside the healthy range does not necessarily mean there is a problem, but it can be a helpful prompt to think about your overall health.
If you have any concerns about your weight, or your result is unexpected, the best step is to speak to your GP or practice nurse.
They can take into account other factors such as your waist measurement, lifestyle, and medical history to give you advice tailored to you.
Important: This calculator is intended for general information only and is not a substitute for professional medical advice. Always consult a qualified healthcare professional regarding any health concerns.