BMI Calculator

BMI (Body Mass Index) is a numerical value calculated from your height and weight using the formula: weight (kg) ÷ height² (m²). It is widely used as a quick screening tool to classify whether a person is underweight, in a healthy range, overweight, or obese — without needing any specialized equipment.

BMI is calculated by dividing your weight in kilograms by the square of your height in metres. For example, a person who weighs 70 kg and is 1.75 m tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9. In imperial units, the formula is: (weight in lbs ÷ height in inches²) × 703.

According to WHO (World Health Organization) guidelines, a BMI between 18.5 and 24.9 is considered the healthy range for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese. However, these thresholds may vary slightly by age and ethnicity.

A BMI of 22 falls in the healthy range (18.5–24.9). A BMI of 25 is the borderline between healthy and overweight. A BMI of 27 is in the overweight range (25–29.9), and a BMI of 30 or above is classified as obese. Each category carries different health implications, though BMI alone is not a definitive diagnosis.

No — BMI is a useful population-level screening tool but has well-known limitations. It cannot distinguish between muscle and fat, so a heavily muscled athlete may register as 'overweight' despite being in excellent health. Conversely, someone with low muscle mass and high body fat (sometimes called 'skinny fat') may show a normal BMI despite having an unfavorable body composition.

The BMI formula and standard categories are the same for both men and women, but the interpretation can differ. Women naturally carry a higher percentage of body fat than men at the same BMI. Some researchers argue that separate BMI thresholds for men and women would be more clinically accurate, though the standard WHO ranges are still universally applied.

Not in the same way. For people under 18, a separate metric called BMI-for-age percentile is used, which factors in age and sex alongside height and weight. A child is considered healthy between the 5th and 85th percentile, overweight between the 85th and 95th, and obese above the 95th percentile for their age group.

Yes — this is an important nuance. Research shows that people of South Asian, East Asian, and Middle Eastern descent tend to develop metabolic health risks at lower BMI values than people of European descent. For these groups, a BMI of 23 or above may already indicate elevated health risk, which is why some health authorities use adjusted thresholds.

For the Indian population, health authorities such as the Indian Council of Medical Research (ICMR) recommend a healthy BMI range of 18.5–22.9 — slightly lower than the standard WHO range. A BMI of 23–24.9 is considered overweight, and 25 or above is classified as obese for Indians, due to higher cardiometabolic risk at lower body weights.

Yes. A condition sometimes called 'metabolically obese normal weight' (MONW) or 'skinny fat' occurs when someone has a normal BMI but carries excess visceral fat around the abdominal organs. This can increase the risk of type 2 diabetes, heart disease, and other metabolic conditions despite a deceptively normal BMI reading.

No — BMI is best used as one data point among many. A more comprehensive picture of your health includes waist circumference, body fat percentage, blood pressure, fasting blood glucose, cholesterol levels, sleep quality, and fitness level. Think of BMI as a preliminary indicator, not a definitive verdict on your health.

The most sustainable way to lower BMI is through a moderate calorie deficit combined with regular physical activity — particularly strength training to preserve muscle mass. Crash diets may reduce BMI rapidly but often lead to muscle loss and metabolic adaptation. Aiming for a gradual weight loss of 0.5–1 kg per week is generally considered the most efficacious long-term approach.