BMI (body mass index) = weight in kilograms ÷ (height in metres)². For adults, the World Health Organization calls 18.5 to 24.9 a healthy range. For people of South Asian background, including Pakistanis, Indians and Bangladeshis, a WHO expert consultation suggested lower action points: 23 and above for increased risk and 27.5 and above for high risk.
You can find your number in seconds with the BMI calculator, which shows both the WHO category and the Asian cut-off. This guide explains what the numbers mean and where BMI falls short. It is general information, not medical advice.
How to calculate BMI
Square your height in metres, then divide your weight by it. Someone 1.70 m tall weighing 70 kg: 1.70 × 1.70 = 2.89, and 70 ÷ 2.89 = 24.2.
In feet and pounds, turn your height into inches and use BMI = 703 × pounds ÷ inches². For 5 feet 7 inches (67 inches) and 154 lb: 703 × 154 ÷ (67 × 67) = 24.1. Height in centimetres? Divide by 100 to get metres. The feet to cm converter and kg to lbs converter help if your measurements are in mixed units.
WHO BMI categories for adults
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy (normal) weight |
| 25 – 29.9 | Overweight (pre-obese) |
| 30 – 34.9 | Obesity class I |
| 35 – 39.9 | Obesity class II |
| 40 and above | Obesity class III |
These cut-offs apply to adults aged 18 and over, men and women alike. Children and teenagers are assessed with BMI-for-age charts instead, because their bodies are still growing.
Why South Asians have lower cut-offs
Research has found that many Asian populations, and South Asians in particular, tend to carry more body fat and develop type 2 diabetes and heart disease at a lower BMI than European populations. In 2004 a WHO expert consultation reviewed this evidence. It kept the international categories but identified additional public health action points for Asian populations:
- BMI 23 or more: increased risk
- BMI 27.5 or more: high risk
In practice, many doctors and health guidelines for South Asian patients aim for a BMI below 23 and start talking about weight-related risk earlier than they would at 25. Our calculator shows where you fall on this Asian scale as well as the WHO one.
Healthy weight for your height
Reversing the formula gives a weight range for any height: weight = BMI × height². The table uses the WHO healthy range (18.5 to 24.9) and the upper weight for a BMI below 23 (22.9).
| Height | Approx. feet | Healthy range, WHO (kg) | Upper weight for BMI under 23 (kg) |
|---|---|---|---|
| 150 cm | 4 ft 11 in | 41.6 – 56.0 | 51.5 |
| 155 cm | 5 ft 1 in | 44.4 – 59.8 | 55.0 |
| 160 cm | 5 ft 3 in | 47.4 – 63.7 | 58.6 |
| 165 cm | 5 ft 5 in | 50.4 – 67.8 | 62.3 |
| 170 cm | 5 ft 7 in | 53.5 – 72.0 | 66.2 |
| 175 cm | 5 ft 9 in | 56.7 – 76.3 | 70.1 |
| 180 cm | 5 ft 11 in | 59.9 – 80.7 | 74.2 |
| 185 cm | 6 ft 1 in | 63.3 – 85.2 | 78.4 |
| 190 cm | 6 ft 3 in | 66.8 – 89.9 | 82.7 |
For example, at 165 cm the WHO healthy range is about 50.4 to 67.8 kg, but staying under the Asian action point of 23 means keeping below about 62.3 kg. The calculator gives the exact figures for your own height.
What BMI doesn’t tell you
BMI is a quick screening number. It’s useful because it needs only a tape measure and scales, but it has real limits:
- Muscle vs fat. Muscle is heavy, so athletes and people who do heavy physical work can have a high BMI without much body fat.
- Where fat sits. Fat around the waist is linked to higher risk than fat elsewhere. Waist size is often checked alongside BMI.
- Age and sex. Older adults tend to have less muscle, so the same BMI can mean more body fat.
- Pregnancy. BMI isn’t meaningful during pregnancy.
So a BMI result is a reason to ask questions, not a diagnosis. If yours is outside the healthy range, or you have concerns such as a family history of diabetes, speak to a doctor, who can look at your blood pressure, blood sugar and other measures. Don’t start a strict diet based on BMI alone.
Frequently asked questions
What is a healthy BMI for Pakistani adults?
The WHO healthy range is 18.5 to 24.9, but for South Asian adults a WHO expert group flagged increased risk from 23 and high risk from 27.5. Many doctors aim for below 23.
How do I calculate BMI in feet and inches?
Convert your height to inches, then BMI = 703 × weight in pounds ÷ (inches × inches). The BMI calculator accepts feet, inches and pounds directly.
Is BMI accurate?
It’s a reasonable rough guide for most adults, but it can’t tell muscle from fat or show where fat is stored. Doctors use it alongside waist size and other checks.
Can I use BMI for my child?
No. Children and teenagers need BMI-for-age percentile charts. Ask a doctor or paediatrician to assess a child’s weight.