How BMI is calculated
BMI (body mass index) is your weight in kilograms divided by your height in metres squared: BMI = kg ÷ m². A person who is 70 kg and 1.70 m tall has a BMI of 70 ÷ 2.89 = 24.2. Feet and pounds are converted first (1 ft = 30.48 cm, 1 lb = 0.4536 kg).
WHO versus Asian cut-offs
The WHO global scale calls 18.5 to 24.9 normal, 25 to 29.9 overweight and 30 or more obese. The WHO Asia-Pacific guidance for South Asians lowers the lines: 23 to 24.9 is overweight (at risk) and 25 or more is obese, because health risks rise at a lower BMI in our population. The table above highlights the category you fall in.
Using the result wisely
- BMI is a quick screen. Waist size, family history, blood sugar and fitness matter too.
- Muscular people, pregnant women and people over 65 may read differently.
- The healthy weight range shown is simply the weights that give a normal BMI at your height.
This tool is for adults aged 18 and over and is not medical advice.
Frequently asked questions
What is a healthy BMI?
For adults, the WHO says 18.5 to 24.9 is the normal range. For South Asians the Asia-Pacific guidance flags health risk earlier: 23 to 24.9 is overweight (at risk) and 25 or more is obese.
Why show both WHO and Asian cut-offs?
People of South Asian origin tend to carry more body fat and have higher diabetes and heart risk at a lower BMI. That is why many doctors in Pakistan look at the Asian cut-offs. Pick the scale your doctor uses.
Is BMI accurate for gym-goers or athletes?
No. Muscle weighs more than fat, so a muscular person can show a high BMI while being lean. Waist size and body-fat percentage tell you more in that case.
Can teenagers and children use this?
No. For under 18s, BMI must be compared against age- and sex-specific growth charts, which this tool does not use.
How do I enter my height in feet?
Switch to ft/in, then type feet and inches separately, for example 5 and 7 for five feet seven inches. You can also use pounds instead of kilograms.