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BMI Calculator

Check your body mass index and see whether your weight is healthy for your height. Adults get Asian (India) or WHO categories; children and teens aged 2–19 get a BMI-for-age percentile for boys or girls.

Formulas last reviewed: September 2026

Disclaimer: Results are general estimates for information and education only. They are not medical advice, a diagnosis or a treatment plan. Please talk to a doctor or qualified health professional before making health, diet, exercise or pregnancy decisions.

What is BMI and why does it matter?

Body mass index (BMI) compares your weight with your height. Doctors and public-health programmes use it as a fast screening tool to spot weight that may be too low, or high enough to raise the risk of diabetes, high blood pressure and heart disease.

For Indians, the cut-offs are different: South Asians tend to carry more body fat, especially around the belly, at the same BMI. That is why this calculator defaults to the Asian (India) ranges and also shows the standard WHO ranges.

Gender and age. For adults (20 and over) the BMI number and the categories are the same for men and women. Gender changes the result in two places: the percentile for children and teens (2–19), who are compared with boys or girls of the same age, and the body-fat estimate, because women carry more body fat than men at the same BMI.

How it is calculated

BMI = weight (kg) ÷ height (m)²

Divide your weight in kilograms by your height in metres, squared. The result is compared with the ranges for underweight, normal, overweight and obese.

Worked example

70 kg and 170 cm

BMI
24.2
Asian / India
Overweight (at risk)
WHO standard
Normal
Healthy weight (Asian)
53.5 – 66.2 kg

The same person can be “normal” on WHO ranges but “at risk” on Asian ranges.

BMI ranges for adults, and for children and teens

For ages 2 to 19 these adult ranges do not apply. A child's BMI is compared with children of the same age and gender (CDC growth charts): below the 5th percentile is underweight, 5th to below the 85th is a healthy weight, 85th to below the 95th is overweight, and the 95th or higher is obesity.

Category (20 and over)Asian / IndiaWHO
Underweight – severe thinnessbelow 16below 16
Underweight – moderate thinness16 – 16.916 – 16.9
Underweight – mild thinness17 – 18.417 – 18.4
Normal18.5 – 22.918.5 – 24.9
Overweight23 – 24.9 (at risk)25 – 29.9
Obese class I25 – 29.930 – 34.9
Obese class II30 and above35 – 39.9
Obese class IIIincluded in class II40 and above

BMI does not measure body fat or muscle. Athletes, older adults and people with a very short or tall frame can be misjudged. Use it with waist size and a doctor's advice.

Frequently asked questions

What is a healthy BMI for Indians?

Between 18.5 and 22.9 on the Asian cut-offs. A BMI of 23 to 24.9 is considered overweight with increased risk, and 25 or more is obesity.

Is BMI accurate for bodybuilders or athletes?

Not always. Muscle is heavier than fat, so a muscular person can have a high BMI with low body fat. Body fat percentage and waist size give a better picture.

Can I use this BMI calculator for children?

Yes, for ages 2 to 19. Choose the gender and enter the age in years and months, and the result is a BMI-for-age percentile from the CDC growth charts. Because children are still growing, talk to a paediatrician before changing a child's diet.

Does gender change my BMI or my category?

Not for adults. BMI is weight divided by height squared, and the adult categories are the same for men and women. Gender matters for children and teens, whose percentile is worked out separately for boys and girls, and for the body-fat estimate, which is higher for women at the same BMI.

How fast should I change my weight?

A gradual change of about 0.25 to 0.5 kg a week is usually safe and easier to keep off. Sudden crash diets often cost muscle and are hard to sustain.