Body Adiposity Index (BAI) Calculator

How it is calculated

The index is BAI = hip / heightm1.5 − 18. Hip is the circumference at the widest point in centimetres, and height is entered in centimetres too; the tool divides it by 100 to get metres before applying the 1.5 power. The result is shown as a percentage. The category depends on the sex selected, because the cut-offs differ. For women: below 21 underweight, 21 to under 33 healthy, 33 to under 39 overweight, 39 and above obese. For men: below 8 underweight, 8 to under 21 healthy, 21 to under 26 overweight, 26 and above obese. Zero, negative or empty values give no result. Weight is not used at all.

Common mistakes

• Entering height in metres (1.65). The field takes centimetres, and 1.65 produces a meaningless result in the tens of thousands of percent.
• Measuring the waist or the belt line instead of the hip. The formula needs the widest circumference around the buttocks.
• Leaving the sex on the default, male. The same BAI falls in a different category for women, so the label can be wrong by two bands.
• Reading the number as a measured body-fat test. It is an estimate from two measurements, so treat the category as a rough guide.
• Measuring the hip over thick clothing, which adds centimetres directly into the result.