BMI Calculator

1. 1Choose metric or imperial units.
2. 2Enter your height and weight.
3. 3Read your BMI, the category it falls in, and the healthy weight range for your height.

BMI divides weight in kilograms by height in metres squared. Imperial figures are converted first: pounds to kilograms and feet and inches to metres, so both unit systems give exactly the same answer.

The categories shown are the World Health Organization's adult thresholds — under 18.5 underweight, 18.5 to 24.9 healthy, 25 to 29.9 overweight, 30 and above obese. The healthy weight range is the reverse calculation: the weights that put a BMI of 18.5 and 24.9 at your height.

BMI is a population-level screening measure, and it has real limits on individuals. It does not distinguish muscle from fat, so athletes often read as overweight; it does not account for body composition, fat distribution, age or ethnicity, and it is not valid for children, pregnancy, or people with a very short or very tall stature. Treat it as one rough indicator among several.

Someone 1.75 m tall weighing 72 kg

1. Height squared = 1.75 × 1.75 = 3.0625
2. BMI = 72 ÷ 3.0625

Result: A BMI of 23.5, which is in the healthy range. For that height, 56.7–76.3 kg is the healthy band.

• Measure your height without shoes, standing straight against a wall; height errors matter because they are squared.
• Weigh yourself at the same time of day, ideally in the morning.
• Watch the trend over weeks rather than a single reading.
• Use waist measurement alongside BMI; it says more about where fat is carried.

• What your BMI means — and what it cannot tell you
• Height in feet and inches to centimetres, and back
• What is a healthy weight for my height?
• BMI cut-offs for Asian adults: why 23 matters
• Stones and pounds to kg: why 11.5 stone isn’t 11 st 5 lb