Use our BMI calculator to work out your body mass index in metric or imperial units. Your result is calculated in your browser and never leaves your device.
How this BMI calculator works it out
Body mass index is your weight in kilograms divided by your height in metres squared: BMI = kg ÷ m². For example, someone 170 cm tall weighing 80 kg has a BMI of 80 ÷ (1.70 × 1.70) = 27.7.
BMI categories for adults
| BMI | Category (Health Canada / WHO) |
|---|---|
| Under 18.5 | Underweight |
| 18.5 to 24.9 | Normal weight |
| 25.0 to 29.9 | Overweight |
| 30.0 to 34.9 | Obese class I |
| 35.0 to 39.9 | Obese class II |
| 40.0 and over | Obese class III |
What BMI does and doesn’t tell you
BMI is a quick screening number. It doesn’t distinguish muscle from fat, doesn’t show where fat is carried, and works less well for older adults, athletes and some ethnic groups. Clinicians use it together with waist circumference, blood pressure, blood tests and your health history. It is not used during pregnancy or for anyone under 18.
When does BMI matter for a medical assessment?
Canada’s adult obesity guideline suggests a clinician may consider prescription treatment for adults with a BMI of 30 or more, or 27 or more with a weight-related condition such as high blood pressure, type 2 diabetes or sleep apnea. If that describes you, a licensed clinician can assess you online. Learn about medical weight management.
What is a healthy BMI?
For most adults, a BMI from 18.5 to 24.9 is considered the healthy range. Your clinician may set a different target based on your age, build and health.
How do I calculate BMI in pounds and feet?
Choose Imperial in the calculator above and enter feet, inches and pounds. The calculator converts to metric for you: BMI = (pounds × 703) ÷ (inches × inches).
Is BMI accurate for muscular people?
Not always. Muscle is denser than fat, so very muscular people can have a high BMI without excess body fat. That is why clinicians never use BMI alone.