BMI Calculator

Calculate body mass index from height and weight.

BMI categories for adults

• Below 18.5: underweight range
• 18.5 to 24.9: healthy weight range
• 25.0 to 29.9: overweight range
• 30.0 and above: obesity range

These are the standard adult ranges used by health organizations such as the CDC and WHO. They are screening categories, not a diagnosis.

Worked example

A person who weighs 70 kg and is 175 cm (1.75 m) tall has a BMI of 70 ÷ (1.75 × 1.75) = 22.9, which falls in the healthy weight range. In US units, 154 lb and 69 inches gives 703 × 154 ÷ (69 × 69) = about 22.7.

How it is calculated

BMI = weight in kilograms ÷ height in meters squared. In US units, BMI = 703 × weight in pounds ÷ height in inches squared.

Frequently asked questions

Is BMI a diagnosis of health?

No. BMI is a quick screening number based only on height and weight. It does not measure body fat, muscle, bone density or where fat is stored, so it cannot tell you how healthy you are on its own. A doctor can interpret it alongside other measures.

Why can BMI be misleading for some people?

People with a lot of muscle can have a high BMI without excess body fat. BMI can also be less accurate for older adults, for people who are very short or very tall, and for some ethnic groups.

Is BMI the same for men and women?

For adults, the same categories are used for men and women. For children and teens, BMI is interpreted by age and sex using growth charts, so this calculator is for adults only.

What should I do with my result?

Treat it as one piece of information. If you have questions about your weight or health, talk to a doctor or registered dietitian who can look at your whole situation.

This calculator is for general information only and is not medical advice.