BMI Calculator – Body Mass Index

Our free BMI Calculator helps you check your Body Mass Index instantly. Enter your weight in kilograms and height in centimetres to find out if you are underweight, normal, overweight, or obese.

What is BMI?

Body Mass Index (BMI) is a numerical value derived from a person's weight and height. It provides a reliable indicator of body fatness for most people and is used to screen for weight categories that may lead to health problems.

BMI Formula

The standard BMI formula is:

BMI = weight (kg) / height (m)²

BMI Categories

• Underweight: BMI < 18.5
• Normal weight: 18.5 – 24.9
• Overweight: 25 – 29.9
• Obese (Class I): 30 – 34.9
• Obese (Class II): 35 – 39.9
• Obese (Class III): ≥ 40

Example

Weight: 70 kg, Height: 175 cm (1.75 m)
BMI = 70 / (1.75)² = 70 / 3.0625 = 22.86 → Normal weight

Frequently Asked Questions

Is BMI accurate for everyone?

BMI is a general screening tool. It may not accurately reflect body fat in athletes, elderly people, or those with high muscle mass. Consult a doctor for a complete assessment.

What is a healthy BMI range?

A BMI between 18.5 and 24.9 is considered normal and healthy for most adults.

Does BMI apply to children?

For children and adolescents, BMI is interpreted differently using age- and sex-specific percentile charts rather than fixed cutoffs.