BMI Calculator

BMI Calculator

Use the calculator below to calculate your BMI (also known as the Quetelet index) which was invented by Lambert Adolphe Jacques Quetele, a Belgian mathematician born in the 18th Century.

How BMI works

Your Body Mass Index is a number that is used to classifying your weight relative to an ideal weight for your height, based on body fat, for those aged 18 to 65.

BMI formula

The formula for BMI is:

  • Imperial Units: BMI = ( weight (lb) * 4.88 ) / height2 (ft2)
  • SI Units: BMI = weight (kg) / height2 (m2)


unit US    
height ftin
weight lb
height cm
weight kg

BMI criticisms

Many people argue that BMI is not a useful evaluation of someone’s health. For example, many people lose height as they age. BMI does not take this into account and hence one’s BMI would increase without any gain in weight as they aged.

Due to this, several alternative systems such as Fat-Free Mass Index and Fat Mass Index have been proposed but have failed to catch on like BMI has.

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