How this calculator works
Both measurements are converted to kilograms and metres before calculation. Changing a unit keeps the same physical measurement. BMI describes weight relative to height; it does not measure body fat directly or diagnose a health condition. The result is an estimate for information only and is not medical advice.
Formula
BMI = weight in kilograms / (height in metres)².
Worked example
For a height of 180 cm and weight of 81 kg, BMI = 81 / 1.8² = 25.0. At 70 inches and 180 lb, the result is approximately 25.8.
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Frequently asked questions
Can I use pounds and inches?
Yes. Choose lb for weight and in for height. The calculation uses exact international unit conversions before applying the metric formula.
Does BMI give a complete picture of health?
No. Muscle mass, age and other factors affect its interpretation. Adult BMI guidance is not intended for children or pregnancy. Discuss individual concerns with a qualified health professional.
How do I enter a height such as 5 ft 6 in?
Enter decimal feet, so 5 ft 6 in is 5.5 ft, or convert the height to inches and choose inches. The field takes one number and a unit.