BMI Calculator
Check your body mass index and health category based on WHO metrics.
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Quick Tip
Enter your weight in kilograms.
About This Tool
Why use BMI Calculator?
Body mass index is weight in kilograms divided by height in metres squared. Enter your weight in kg and height in cm and this calculator returns your BMI and the category it falls into under the World Health Organization scale.
For 68 kg at 170 cm: 68 ÷ 1.7² = 23.5, which is in the healthy range. The categories are under 18.5 underweight, 18.5–24.9 healthy, 25–29.9 overweight and 30 or above obese. BMI is a screening tool built from height and weight alone, so it cannot distinguish muscle from fat and should be read alongside other measures.
Key Benefits
Standard WHO categories
The same thresholds used in clinical and public health guidance.
Instant recalculation
Change either figure and the result updates, which makes it easy to see the effect of a target weight.
Simple metric inputs
Kilograms and centimetres, the units used on most health forms outside the US.
How to use BMI Calculator
- 1
Enter your weight in kilograms.
- 2
Enter your height in centimetres.
- 3
Read your BMI and its category.
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Treat the result as one indicator, not a diagnosis.
Best use cases
Check your BMI for a health form or a check-up.
See what weight would move you into the healthy range.
Track BMI alongside weight over time.
Answer BMI questions in a biology or health class.
BMI Calculator FAQs
What is a healthy BMI?
18.5 to 24.9 for most adults. Some health bodies use a lower upper limit of 23 for people of South Asian descent because of different health risks at the same BMI.
How do I calculate BMI in pounds and inches?
BMI = weight (lb) ÷ height (in)² × 703. For 150 lb at 66 in: 150 ÷ 4,356 × 703 = 24.2.
Is BMI accurate for everyone?
No. It overestimates body fat in muscular people and can underestimate it in older adults who have lost muscle. It is also not used in this form for children, who are assessed on growth percentiles.
What should I do if my BMI is outside the healthy range?
Treat it as a prompt to look further rather than a verdict. Waist measurement, blood pressure and blood tests tell you more, and a clinician can interpret them together.
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