Body Mass Index

Body Mass Index compares a person’s mass with their height squared, so taller people are not judged as having “too much” mass just because they are bigger overall. Squaring height helps the ratio scale more fairly across different body sizes, giving a simple number that can be used as a quick screening measure rather than a full health diagnosis. It is useful for spotting possible underweight, healthy-weight, overweight, or obesity ranges, but it does not measure body fat directly.

Use BMI when you need a fast, basic check of whether a person’s weight is in a range that may need follow-up. It is commonly used in general health checks, clinics, and fitness or public-health screening.

• Using height in centimetres instead of metres
• Forgetting to square the height before dividing
• Treating BMI as a direct measure of body fat or overall health