BMI Calculator
Body mass index and healthy weight range
- Underweight
- 0.0 – 18.5
- Normal
- 18.5 – 23.0
- Overweight
- 23.0 – 25.0You
- Obese
- 25.0 and above
Understand the result
About the BMI Calculator
What is BMI?
Body mass index (BMI) is your weight in kilograms divided by the square of your height in metres. It is a quick screening measure for whether your weight is in a healthy range for your height. For Indians and other Asian populations, health risks such as diabetes and heart disease rise at lower BMIs, so Indian guidelines use lower cut-offs than the international WHO scale.
This BMI calculator works in metric or imperial units, shows your BMI category on either the Asian-Indian or the WHO scale, and the healthy weight range for your height.
How this calculator works
Body mass index divides weight in kilograms by height in metres squared. It is a quick way to compare weight across people of different heights, which is exactly what it was designed for — population screening, not individual diagnosis.
India and much of Asia use lower cut-offs than the WHO international scale, because research shows higher body-fat percentage and metabolic risk at a given BMI in South Asian populations. The overweight threshold is 23 rather than 25.
Formula
BMI = weight (kg) ÷ height (m)² Healthy weight range = normal-band BMI × height (m)²
Worked example
- Someone 170 cm tall weighing 70 kg: BMI = 70 ÷ 1.70² = 24.2.
- On the WHO scale that is “normal”; on the Asian-Indian scale it falls in the overweight band.
- Their healthy range on the Asian-Indian scale is roughly 53.5 – 66.5 kg.
BMI categories
| Category | Asian-Indian cut-offs | WHO cut-offs |
|---|---|---|
| Underweight | Below 18.5 | Below 18.5 |
| Normal | 18.5 – 22.9 | 18.5 – 24.9 |
| Overweight | 23 – 24.9 | 25 – 29.9 |
| Obese | 25 and above | 30 and above |
Healthy weight for your height
| Height | Healthy weight range |
|---|---|
| 150 cm (4 ft 11 in) | 41.6 – 51.8 kg |
| 160 cm (5 ft 3 in) | 47.4 – 58.9 kg |
| 170 cm (5 ft 7 in) | 53.5 – 66.5 kg |
| 180 cm (5 ft 11 in) | 59.9 – 74.5 kg |
Waist size adds useful information: for Indian adults, a waist above about 90 cm for men or 80 cm for women suggests excess abdominal fat, even when BMI is normal.
Assumptions & important notes
What this calculator assumes
- BMI treats all body mass alike. Athletes with high muscle mass often register as overweight without excess fat.
- It is not appropriate for children, pregnant women, or people with significant muscle loss.
Important notes
- Waist circumference and waist-to-height ratio often predict metabolic risk better than BMI alone.
- Any change in weight is best planned with a doctor or a registered dietitian rather than from a number on a screen.
Frequently asked questions
Why does India use different BMI cut-offs?
South Asian populations tend to have a higher proportion of body fat and greater risk of diabetes and heart disease at the same BMI. Indian guidelines therefore set the overweight threshold at 23 and obesity at 25.
Is BMI accurate for everyone?
No. It is a screening tool for populations. It cannot tell muscle from fat, ignores where fat is stored, and is unsuitable for children, pregnancy, athletes and the elderly.
What else should I look at?
Waist circumference, waist-to-height ratio, blood pressure, blood sugar and lipid levels together give a far better picture of health than BMI on its own.
Is BMI different for children?
Yes. For children and teenagers, BMI is compared with growth charts for their age and sex rather than fixed adult cut-offs. Ask a paediatrician to interpret a child’s BMI.
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