BMI Calculator
Enter your height and weight in metric or imperial units to get your Body Mass Index, your category and the healthy weight range for your height.
How to calculate your BMI
- Choose metric or imperial units.
- Enter your height and weight. Your BMI, category and position on the scale update instantly.
- Check the healthy weight range for your height and how far you are from it.
Features
Metric & imperial
Centimetres and kilograms, or feet, inches and pounds.
Healthy range
See the weight range that gives a BMI of 18.5–24.9 for your height.
Live results
Numbers update the moment you change an input.
Private
Everything is calculated in your browser; nothing is sent anywhere.
Frequently asked questions
How is BMI calculated?
BMI = weight in kilograms divided by height in metres squared. In imperial units: weight in pounds × 703 ÷ height in inches squared. A 70 kg person who is 1.70 m tall has a BMI of 70 ÷ 2.89 = 24.2.
What are the BMI categories?
For adults: under 18.5 is underweight, 18.5–24.9 is the healthy range, 25–29.9 is overweight and 30 or above is classed as obesity, following WHO guidance.
Is BMI accurate for everyone?
BMI is a screening estimate, not a diagnosis. It does not distinguish muscle from fat, so athletes can score “overweight” while being lean, and it may under-estimate body fat in older adults. Talk to a doctor for a proper assessment.
What is BMI prime?
BMI prime is your BMI divided by 25, the upper limit of the healthy range. A value under 1.0 means you are within or below the healthy range; 1.2 means 20% above the upper limit.