BMI Calculator
Check your Body Mass Index (BMI) — the quickest way to see whether your weight is in a healthy range for your height.
BMI Calculator
Your Body Mass Index and weight category, instantly.
BMI is a screening tool, not a diagnosis — muscle, age and body composition all matter.
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How to use this calculator
- Choose Metric or Imperial.
- Type in your weight and height.
- Press Calculate BMI — your BMI, weight category and healthy range appear instantly.
Formula
Using the example on this page: 70 kg ÷ (1.75 m × 1.75 m) = 22.9.
BMI bands: under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight, 30 and above obese.
Frequently asked questions
What is a healthy BMI?
A BMI between 18.5 and 24.9 is classed as healthy for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classed as obese.
Is BMI accurate for everyone?
Not always. BMI does not distinguish muscle from fat, so very muscular people can score high despite being healthy. It also works differently for children, older adults and some ethnic groups.
What should I do if my BMI is high?
Use it as a prompt to look at your diet and activity levels, and speak to a GP or dietitian for advice tailored to you.