BMI Calculator
Choose metric or imperial units, enter your height and weight, and see your BMI, category, and healthy weight range.
| BMI | |
| Category | |
| Healthy weight range for your height |
How BMI is calculated
Body mass index (BMI) is your weight divided by the square of your height. In metric units the formula is BMI = kg ÷ m². For someone who is 175 cm (1.75 m) tall and weighs 70 kg: 1.75 × 1.75 = 3.0625, and 70 ÷ 3.0625 = 22.9.
In imperial units the formula is BMI = 703 × lb ÷ in². A person who is 5 ft 9 in (69 inches) and weighs 154 lb has a BMI of 703 × 154 ÷ (69 × 69) = 108,262 ÷ 4,761 = 22.7. The factor 703 converts pounds and inches to the metric result.
The standard adult categories used by the World Health Organization and the CDC are: under 18.5 is underweight, 18.5 to 24.9 is normal weight, 25.0 to 29.9 is overweight, and 30.0 or above is obese. The healthy weight range shown is the weight that would give a BMI of 18.5 to 24.9 at your height.
Frequently asked questions
Is BMI accurate for everyone?
BMI is a screening tool, not a diagnosis. It does not distinguish muscle from fat, so very muscular people can score as overweight while having little body fat, and older adults can have a normal BMI with low muscle mass. Athletes, pregnant women, and children should use other measures or age-adjusted charts.
What is a healthy BMI?
For adults, a BMI between 18.5 and 24.9 is considered the normal or healthy range. Some health bodies use lower cutoffs for people of Asian descent, where health risks rise at a BMI of about 23 and above.
Does BMI apply to children and teens?
Not directly. For ages 2 to 19, BMI is calculated the same way but interpreted using age- and sex-specific percentile charts rather than the fixed adult categories shown here.