Question 1

How is BMI calculated?

Accepted Answer

Body Mass Index is your weight in kilograms divided by the square of your height in metres (kg/m²). In imperial units you can multiply weight in pounds by 703 and divide by height in inches squared. The calculator does this automatically in whichever units you choose.

Question 2

What is a healthy BMI range?

Accepted Answer

For most adults, a BMI of 18.5 to 24.9 is considered a healthy weight. Below 18.5 is classed as underweight, 25 to 29.9 as overweight, and 30 or above as obese. These ranges are general guidance for adults and are interpreted differently for children, older adults and some ethnic groups.

Question 3

Is BMI accurate for everyone?

Accepted Answer

BMI is a useful population-level screening tool but it has limits. It does not distinguish muscle from fat, so very muscular people can read as overweight, and it does not account for age, sex, ethnicity or where fat is stored. Treat it as a rough guide and speak to a healthcare professional for a fuller picture.

Question 4

Does BMI differ between metric and imperial units?

Accepted Answer

No — BMI is the same number regardless of the units you use, because the imperial formula simply converts to the same ratio. The calculator lets you enter height and weight in metric or imperial and gives the identical result either way.