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CalcSmart › BMI Calculator

BMI Calculator — Free & Instant

Calculate your Body Mass Index in seconds. Works in metric (cm/kg) and imperial (inches/lbs). See your BMI category and healthy weight range.

cm
kg
Your BMI
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Category—
Healthy weight range—
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What is BMI?

Body Mass Index (BMI) is a simple calculation using a person's height and weight. The formula is BMI = weight (kg) ÷ height² (m²). It is widely used as a screening tool to identify whether a person is underweight, normal weight, overweight, or obese.

BMI Categories (WHO Standard)

Limitations of BMI

BMI is a useful starting point but doesn't account for muscle mass, bone density, age, or fat distribution. Athletes may have a high BMI due to muscle and still be very healthy. Always use BMI alongside other health indicators and consult a healthcare professional for a complete assessment.

Frequently Asked Questions

What is a healthy BMI for adults?+
For most adults, a BMI between 18.5 and 24.9 is considered healthy. However, healthy ranges can vary by age, sex, and ethnicity. Asian populations, for example, may face health risks at lower BMI values and many health organizations recommend a lower threshold of 23 for this group.
How do I calculate BMI manually?+
For metric: divide your weight in kilograms by your height in meters squared. Example: 70 kg ÷ (1.75 × 1.75) = 22.9. For imperial: multiply your weight in pounds by 703, then divide by your height in inches squared.
Is BMI different for men and women?+
The BMI calculation formula is the same for men and women, but healthy body fat percentages differ between the sexes. Women naturally carry more body fat than men at the same BMI, so some experts suggest slightly different interpretations. However, the standard WHO categories above apply to both.
What should I do if my BMI is outside the healthy range?+
A BMI outside the healthy range is a signal to speak with your doctor, not a diagnosis. Your doctor can perform more detailed assessments (waist circumference, body fat percentage, blood work) to get a fuller picture of your health. Lifestyle changes like improved diet and increased physical activity are often the first recommendations.

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