BMI Calculator (Metric)

What is Body Mass Index (BMI)?

Body Mass Index (BMI) is a medical indicator that helps assess whether a person's weight is appropriate for their height. The BMI calculator uses the formula: BMI = weight (kg) ÷ height² (m). This indicator is widely used by healthcare professionals to categorize weight status.

BMI Categories and Their Meaning

• Underweight: BMI less than 18.5
• Normal weight: BMI 18.5-24.9
• Overweight: BMI 25.0-29.9
• Obesity: BMI 30.0 and above

How to Calculate BMI Manually?

To calculate body mass index step by step:

1. Measure your weight in kilograms
2. Measure your height in centimeters and convert to meters
3. Square the height value
4. Divide weight by the obtained value

Example: With 70 kg weight and 175 cm height: BMI = 70 ÷ (1.75)² = 22.86

Limitations of BMI Calculator

It's important to remember that the BMI calculator doesn't account for:

• Muscle mass and body composition
• Body fat distribution
• Age and gender
• Ethnic background

Healthy Lifestyle and Maintaining Normal BMI

To maintain a healthy body mass index, it's recommended to:

• Follow a balanced diet with calorie control
• Engage in regular physical exercise (minimum 150 minutes weekly)
• Get adequate rest (7-9 hours of sleep)
• Manage stress and avoid harmful habits

Common BMI Examples by Height and Weight

Check the BMI for common height and weight combinations:

• 160 cm, 50 kg
• 170 cm, 65 kg
• 175 cm, 80 kg
• 180 cm, 95 kg
• 165 cm, 90 kg

Who the BMI Scale Applies To

The WHO categories on this page are for adults aged 18 and over, and they are the same for men and women: sex does not enter the BMI formula and does not move the category boundaries.

Children and teenagers aged 5–19 are read differently. Their BMI is compared with a WHO reference for age and sex and expressed as a z-score (SDS; WHO publishes the same reference as percentile charts): overweight above +1 SD, obesity above +2 SD, thinness below −2 SD and severe thinness below −3 SD. At the top of that range the two scales meet — WHO notes that +1 SD equals a BMI of 25 at 19 years, and +2 SD equals 30. WHO BMI-for-age (5–19 years)

For older adults the WHO classification above draws no separate line by age. Other guidance does, for a different purpose: the ESPEN consensus on diagnosing malnutrition counts a BMI as reduced below 20 under the age of 70 and below 22 above it. On its own that is not a diagnosis: there it only counts alongside mandatory unintentional weight loss. It is a boundary inside a diagnostic criterion, not a healthy weight range, and this page does not apply it. ESPEN Consensus Statement, Clinical Nutrition, 2015