BMI Calculator
A screening tool, not a diagnosis. Muscle mass and body composition matter too.
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About this bmi calculator
Body mass index (BMI) divides your weight by height squared. It is a quick screening number doctors use before deeper tests — not a diagnosis on its own.
Muscle mass, age, and where you carry fat all matter. Athletes and very muscular adults may read "overweight" despite low body fat. Pair BMI with waist size, activity, and blood pressure for context.
Use this free BMI calculator for instant results with plain-language categories. For a height-based weight range, try our Ideal Weight Calculator next.
Frequently asked questions
What is a healthy BMI for adults? +
For most adults, 18.5–24.9 is considered normal weight. Ranges above 25 suggest overweight; 30+ suggests obesity. Your doctor may interpret results differently based on muscle, age, and health history.
Is BMI accurate for everyone? +
BMI is less accurate for very muscular people, some older adults who lost muscle, and certain ethnic groups. It works best as a starting screening tool, not a final health verdict.
How do I calculate BMI manually? +
Metric: weight (kg) ÷ height (m)². Imperial: 703 × weight (lb) ÷ height (in)². This calculator handles both unit systems automatically.
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