BMI Calculator

Find your body mass index (BMI), the World Health Organization category it falls in, and the weight range for a BMI of 18.5 to 24.9 at your height. BMI is a simple screening number, and it has important limits.

BMI has limits

BMI doesn't tell muscle from fat, and it doesn't work the same for every age, body type, or ethnic background. It's not for people under 18 or during pregnancy. Use it as one piece of information, and talk to a health professional about your health.

Your BMI

22.7

WHO category: 18.5–24.9 (normal weight)
Weight range for BMI 18.5–24.9: 125–169 lb

WHO categories for adults

Below 18.5 (underweight)
18.5–24.9 (normal weight)
25–29.9 (overweight)
30–34.9 (obesity class I)
35–39.9 (obesity class II)
40 or more (obesity class III)

Results are estimates for information only and do not constitute financial, medical, or legal advice.

How BMI is calculated

BMI divides your weight by the square of your height. The World Health Organization groups adult results into categories, from below 18.5 to 40 or more. These categories were designed for populations, so for one person they're only a starting point.

The formula

BMI = weight (kg) ÷ height (m)²

In pounds and inches: BMI = 703 × weight (lb) ÷ height (in)².

Worked example

An adult who weighs 70 kg (154 lb) and is 1.75 m (5 ft 9 in) tall.

Height squared: 1.75 × 1.75 = 3.0625.
BMI: 70 ÷ 3.0625 ≈ 22.9, in the 18.5–24.9 category.

Sources

World Health Organization.Obesity and overweight: fact sheet(adult BMI definitions).

Frequently asked questions

What are the limitations of BMI?

BMI only uses weight and height. It can't tell muscle from fat, so very muscular people may get a high BMI while being healthy. It also doesn't show where fat is stored, and the same BMI can mean different things at different ages, for different body types, and for people of different ethnic backgrounds.

Can children and teens use this calculator?

No. For people under 18, BMI is compared with growth charts for their age and sex, so the adult categories don’t apply. A pediatrician can explain those charts.

What should I do with my result?

Use it as one piece of information about your health, not as a verdict. A health professional can look at the whole picture, including blood pressure, blood tests, activity, and family history.