A BMI (Body Mass Index) calculator determines if your weight is in a healthy range for your height.
Calculate your Body Mass Index to assess whether your weight is in a healthy range.
A BMI calculator computes your Body Mass Index to classify your weight relative to your height. The formula used is:
WHO categories: Underweight (<18.5), Normal (18.5-24.9), Overweight (25-29.9), Obese (≥30). For example, a person weighing 70 kg and 1.75 m tall has a BMI of 22.86 (Normal).
| Category | BMI Range |
|---|---|
| Underweight | < 18.5 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity Class I | 30.0 – 34.9 |
| Obesity Class II | 35.0 – 39.9 |
| Obesity Class III | ≥ 40.0 |
A normal BMI ranges from 18.5 to 24.9 according to the World Health Organization (WHO). Below 18.5 is underweight, 25-29.9 is overweight, and 30 or above is classified as obese.
BMI is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = weight(kg) / height(m)^2. For imperial units, multiply by 703: BMI = (weight(lbs) / height(in)^2) x 703.
BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat, so athletes may have a high BMI despite low body fat. It may also be less accurate for elderly people, pregnant women, and certain ethnic groups.
BMI categories per WHO: Underweight (<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).