The NHS BMI Calculator is a simple and effective tool designed to help individuals determine whether their weight falls within a healthy range based on official NHS guidelines. Body Mass Index (BMI) is an essential measurement used by healthcare professionals to assess weight-related health risks.
This calculator provides an instant BMI score based on your height and weight, helping you make informed decisions about your health.
Maintaining a healthy BMI is crucial for overall well-being. The NHS uses BMI as a screening tool to identify potential risks associated with:
Although BMI does not directly measure body fat percentage, it remains one of the most widely used methods to assess general health risks.
Learn more about BMI: What is BMI?
This tool is suitable for:
✔ Adults aged 18 and over
✔ Men and women of all body types
✔ Individuals who want to monitor their weight for health and fitness goals
However, BMI calculations may not be suitable for certain groups, including:
Follow these four simple steps to calculate your BMI accurately.
Choose your preferred measurement unit:
Measure your height correctly by standing straight and removing shoes.
Use a digital scale for accurate weight measurement.
Need help interpreting weight ranges? View the NHS BMI Chart.
Although BMI is calculated the same way for men and women, certain factors influence interpretation:
Once you enter your details, the NHS BMI Calculator instantly generates your BMI score.
Here's how it works:
BMI = Weight (kg) ÷ Height (m²)
BMI = (Weight (lbs) ÷ Height (inches²)) × 703
Wondering about BMI accuracy? Read How Accurate is BMI?
Your BMI result will be classified into one of these NHS categories:
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Increased risk of malnutrition and weakened immunity |
| 18.5 – 24.9 | Healthy Weight | Lowest health risk |
| 25 – 29.9 | Overweight | Increased risk of heart disease and high blood pressure |
| 30 and above | Obese | High risk of diabetes, joint problems, and stroke |
See the complete NHS BMI classification: NHS BMI Chart
A high BMI is linked to:
✔ Start an NHS-approved weight loss programme.
✔ Follow a balanced diet and regular exercise routine.
NHS guidance on reducing BMI: How to Reduce BMI
A low BMI may indicate:
✔ Increase nutrient-dense foods in your diet.
✔ Follow an NHS-approved weight gain plan.
Read more: How to Gain Weight Safely
Yes, the calculator follows NHS standards, but it does not account for muscle mass, age-related changes, or fat distribution.
More details: How Accurate is BMI?
No, NHS BMI for children is measured using growth percentiles rather than the standard BMI formula.
Learn more: BMI for Children
Find effective workouts: NHS-Recommended Exercises
