BMI Calculator

Enter your weight and height to see your body mass index (BMI), what it means, and the healthy weight range for your height. For adults aged 18 and over.

What is BMI?

Body mass index (BMI) compares your weight with your height. It is a quick way for health workers to see whether an adult's weight is in a range linked with good health. It does not measure body fat directly.

BMI categories for adults

• Below 18.5: underweight
• 18.5 to 24.9: healthy weight
• 25 to 29.9: overweight
• 30 and above: obese

The BMI formula

BMI = weight in kilograms ÷ (height in metres × height in metres). If your height is in centimetres, divide it by 100 first. For example, a woman who weighs 60 kg and is 160 cm (1.6 m) tall has a BMI of 60 ÷ 2.56 = 23.4, which is in the healthy range.

Converting feet and inches

One foot is 12 inches and one inch is 2.54 cm. A height of 5 feet 7 inches is 67 inches, which is 67 × 2.54 = 170.2 cm. The calculator does this conversion for you when you choose feet and inches.

Limits of BMI

• It cannot tell muscle from fat, so athletes may show a high BMI.
• It is not used in the same way for children, teenagers or pregnant women.
• Where fat is stored matters too. A large waist can be a health risk even with a normal BMI.

Frequently Asked Questions

More free tools: Percentage Calculator and Age Calculator.