Use this free BMI (Body Mass Index) calculator to estimate whether your weight is in a healthy range for your height. It works in both metric (cm, kg) and imperial (ft, in, lbs) units and uses the weight categories recognized by Health Canada and the World Health Organization (WHO).
BMI is a screening tool, not a diagnosis. It does not measure body fat directly and can be less accurate for athletes, older adults, and some ethnic groups. Always talk to your family doctor about your healthy weight.
How to Use the BMI Calculator
Enter your height and weight, choose metric or imperial units, and the calculator instantly shows your Body Mass Index and which weight category it falls into. BMI is calculated with a simple formula:
- Metric: weight (kg) ÷ height (m)²
- Imperial: 703 × weight (lb) ÷ height (in)²
BMI Categories (Health Canada / WHO)
For most adults aged 18 and over, the following ranges apply:
| BMI Range | Category | What It Generally Means |
|---|---|---|
| Below 18.5 | Underweight | May signal undernutrition or an underlying condition |
| 18.5 – 24.9 | Healthy weight | Lowest risk range for most adults |
| 25.0 – 29.9 | Overweight | Increased risk of some chronic conditions |
| 30.0 and above | Obese | Higher risk of heart disease, type 2 diabetes, and more |
What BMI Does Not Tell You
BMI is a quick screening tool, but it has real limits. It does not distinguish muscle from fat, so very muscular people can score “overweight” while being healthy. It can also be less accurate for older adults, pregnant people, and some ethnic backgrounds — Health Canada notes that health risks can rise at lower BMI thresholds for certain populations. Waist circumference and overall lifestyle matter just as much as a single number.
For the bigger picture on healthy living, see our guides on cancer prevention, a healthier heart, the role of dietary fibre, and cutting back on processed foods.
When to Talk to a Doctor
If your BMI falls outside the healthy range — or if you have concerns about your weight regardless of your BMI — book an appointment with your family doctor or visit a walk-in clinic. They can assess your overall health, not just one number, and help you set realistic, safe goals.