BMI Calculator
Find your Body Mass Index and its classification. Free, no sign-up.
What BMI is and how to read it
BMI (Body Mass Index) relates weight and height. It is used as an initial screen, but it does not measure fat directly — so it should accompany a full physical assessment.
Classification table (WHO)
- Under 18.5 — Underweight
- 18.5 to 24.9 — Normal 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 or more — Obesity class III
For athletes, BMI may overestimate fat — combine it with body fat percentage and TDEE.
Frequently asked questions
What is BMI?
BMI (Body Mass Index) is the ratio of weight to height squared (kg/m²). It is a quick screening indicator to classify underweight, normal weight, overweight and obesity.
How do you calculate BMI?
Divide weight (in kg) by height (in meters) squared. Example: 70 kg and 1.75 m → 70 / (1.75 × 1.75) = 22.9.
Is BMI accurate for athletes?
With caveats. Very muscular people can have a high BMI without excess fat, because muscle weighs more. Combine BMI with a physical assessment and body fat percentage.
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