What is BMI?
Body Mass Index (BMI) is a simple calculation that uses your height and weight to estimate whether you have a healthy body weight. It is widely used by healthcare professionals in the UK as a screening tool to identify potential weight-related health risks.
How to Calculate BMI
The BMI formula is: weight (kg) / height² (m²). For example, if you weigh 70kg and are 1.75m tall, your BMI would be 70 / (1.75 × 1.75) = 22.9, which falls within the healthy range.
NHS BMI Guidelines
According to the NHS in the United Kingdom, BMI results are interpreted as follows:
- Below 18.5 — Underweight
- 18.5 to 24.9 — Healthy weight
- 25 to 29.9 — Overweight
- 30 to 39.9 — Obese
- 40 and above — Severely obese
Limitations of BMI
While BMI is a useful screening tool, it has limitations. It does not account for muscle mass, bone density, body composition, or fat distribution. Athletes with high muscle mass may have a higher BMI without having excess body fat. Similarly, older adults may have a healthy BMI but reduced muscle mass.
Use Our BMI Calculator
Try our free BMI calculator to check your BMI instantly. It uses the same formula as the NHS and provides clear guidance on your results.