Question 1

How is BMI calculated?

Accepted Answer

BMI is your weight in kilograms divided by the square of your height in metres (kg/m²). In imperial units it is weight in pounds divided by height in inches squared, multiplied by 703. This calculator does the conversion for you whichever units you use.

Question 2

What is a healthy BMI?

Accepted Answer

For most adults a BMI between 18.5 and 24.9 is classed as a healthy weight. Below 18.5 is underweight, 25 to 29.9 is overweight, and 30 or above is in the obese range. The calculator shows where you fall on a colour-coded scale.

Question 3

Is BMI accurate for everyone?

Accepted Answer

BMI is a useful screening tool but not a perfect measure of health. It does not distinguish muscle from fat, so very muscular people can read as 'overweight', and it is interpreted differently for children, older adults, pregnant women and some ethnic groups. Treat it as a guide and talk to a doctor about your individual health.

Question 4

What is my healthy weight range?

Accepted Answer

It is the range of weights that gives a BMI between 18.5 and 24.9 for your height. The calculator works it out and shows it in your chosen units, so you can see roughly how much you would need to gain or lose to be in the healthy range.

Question 5

Does the BMI calculator store my details?

Accepted Answer

No. Your height and weight are used only in your browser to do the calculation and are never sent to or stored on a server.

BMI Calculator

How to use the BMI calculator

BMI categories for adults

Frequently asked questions