BMI Calculator
Calculate your body mass index in centimetres and kilograms or feet, inches and pounds. See your BMI category and the healthy weight range for your height.
BMI categories for adults
| BMI | Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Normal (healthy) weight |
| 25.0 to 29.9 | Overweight |
| 30.0 to 34.9 | Obesity class I |
| 35.0 to 39.9 | Obesity class II |
| 40.0 and above | Obesity class III |
These are the World Health Organization categories, also used by Health Canada for adults aged 18 and over.
The BMI formula
BMI = weight in kilograms / (height in metres)². A person who is 1.70 m tall and weighs 70 kg has a BMI of 70 / (1.70 x 1.70) = 24.2.
In imperial units: BMI = 703 x weight in pounds / (height in inches)². At 5 ft 10 in (70 inches) and 180 lb: 703 x 180 / 4,900 = 25.8.
What BMI does not tell you
BMI is a quick screening number, not a diagnosis. It does not measure body fat directly, so very muscular people can show a high BMI while being lean. It can also underestimate risk in older adults who have lost muscle. Waist circumference, blood pressure, blood work and your health history give a more complete picture.
BMI for children and teens is calculated the same way but read on age- and sex-specific growth charts, so this calculator is for adults only.
Related tools: Calorie calculator, Age calculator, Unit converter, Pregnancy due date.
FAQ
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered a healthy weight range.
Is BMI different for men and women?
The formula and adult categories are the same for men and women. Body composition differs, which is one reason BMI is only a screening tool.
How do I calculate BMI with feet and inches?
Convert your height to inches (feet x 12 + inches), then use BMI = 703 x pounds / inches². The calculator does this for you in imperial mode.
Can I use BMI during pregnancy?
No. Weight changes during pregnancy are expected. Your pre-pregnancy BMI is used to guide healthy weight gain; ask your health care provider.