BMI Calculator
Calculate your Body Mass Index and check your health category.
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BMI Score
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Ideal Weight Range
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Health Advice
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Enter your height and weight and click Calculate BMI.
How to Use This Tool
- Enter the required values into the BMI Calculator input fields shown above.
- The BMI Calculator recalculates automatically as soon as all required inputs are filled in.
- Review the breakdown of the result and adjust any input to instantly see how the outcome changes.
Common Use Cases
- Health screening: Primary care nurses compute BMI as an initial obesity screen during routine annual physicals.
- Insurance underwriting: Life insurance applications use BMI as one factor in risk class assignment alongside blood pressure and cholesterol.
- Personal fitness tracking: Individuals monitor BMI alongside weight to set ranges, though body fat percentage is more accurate for athletes.
Frequently Asked Questions
What's the formula for BMI?
BMI = weight (kg) / height (m)^2. For pounds and inches: BMI = (weight_lb / height_in^2) * 703. A 70 kg person 1.75 m tall has BMI 22.9, in the WHO "normal weight" range of 18.5-24.9.
What are the BMI categories?
WHO classifies: under 18.5 underweight, 18.5-24.9 normal, 25-29.9 overweight, 30-34.9 obesity class I, 35-39.9 class II, 40+ class III. These cutoffs are based on Caucasian populations; some Asian guidelines use lower thresholds (overweight starts at 23).
Why is BMI inaccurate for athletes?
BMI doesn't distinguish muscle from fat. A 1.85 m, 100 kg bodybuilder has BMI 29.2 ("overweight") despite low body fat. For muscular populations, body fat percentage via DEXA or skinfold calipers is a better measure than BMI alone.