BMI Calculator

Body mass index is a single number calculated from height and weight. In metric units it is weight in kilograms divided by height in metres squared; the imperial version uses pounds and inches with a conversion factor. This calculator accepts either and shows the result alongside the category the figure falls into under the standard adult ranges.

BMI was designed in the nineteenth century to describe populations, not individuals, and that is still what it does best. It takes no account of how much of a person's weight is muscle, where that weight sits, or differences between age groups and ancestries. A very muscular athlete and a sedentary person of the same height and weight get the same number, which tells you something about the limits of the measure.

Treat the result as one rough indicator among many. It is not a diagnosis and it says nothing about your health on its own. Anyone with a question about their weight or health should speak to a doctor or another qualified healthcare professional, who can consider the full picture.

• Metric and imperial units with instant switching
• Feet and inches entered separately for convenience
• Standard adult BMI categories
• Clear explanation of the formula used
• Notes on what BMI cannot measure
• Everything calculated in your browser with nothing stored

The bmi calculator is used by writers, developers, students, marketers and anyone else who needs the job done once without installing software. Common cases include:

• Converting a BMI figure between unit systems
• Understanding a number quoted in a health article
• Checking the arithmetic behind a BMI you were given
• Learning how the formula works
• Preparing a question to raise with a healthcare professional