How to read your BMI
Body Mass Index (BMI) estimates whether your weight is in a healthy range for your height. It's calculated as your weight in kilograms divided by the square of your height in metres. Because it's quick and needs only two numbers, clinicians use it as a first-pass screen — but it's a starting point for a conversation, not a diagnosis.
Adult BMI categories
- Under 18.5 — underweight
- 18.5–24.9 — healthy weight
- 25.0–29.9 — overweight
- 30.0 and above — obese
When to see a doctor about your weight
If your BMI sits outside the healthy range — or you've had a rapid unexplained change in weight — it's worth a check-in. A clinician can look at the fuller picture (waist measurement, blood pressure, blood sugar, medications, family history) that BMI alone misses. You can find a family doctor or walk-in clinic near you on CanClinics, or read more about what a family practice does.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI between 18.5 and 24.9 is considered the healthy weight range. 25–29.9 is classed as overweight and 30 or above as obese. These ranges are screening guides, not diagnoses.
Is BMI accurate?
BMI is a useful population-level screening tool but has real limits for individuals: it can't tell muscle from fat, and it doesn't account for age, sex, ethnicity, or where you carry weight. Athletes often read as "overweight" despite low body fat. Treat it as one signal, not the whole picture.
Does BMI work for children?
No — this calculator is for adults 20 and over. Children and teens use age- and sex-specific BMI percentiles. Ask your family doctor or pediatrician to interpret a child's BMI.