Body Composition
BMI Calculator — Body Mass Index
Calculate your Body Mass Index (BMI) instantly using the WHO-standard formula. Understand your weight category and get personalized health insights.
Enter Your Measurements
BMI Classification Chart (WHO)
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Nutritional deficiency risks |
| 18.5 – 24.9 | Normal weight | Lowest health risk |
| 25.0 – 29.9 | Overweight | Moderate risk |
| 30.0 – 34.9 | Obese (Class I) | High risk |
| 35.0 – 39.9 | Obese (Class II) | Very high risk |
| 40.0 and above | Obese (Class III) | Extremely high risk |
How the BMI Calculator Works
The BMI calculator uses the Body Mass Index formula established by the World Health Organization (WHO) and widely used by healthcare professionals worldwide.
BMI Formula
Metric: BMI = weight (kg) ÷ height² (m)
Imperial: BMI = 703 × weight (lbs) ÷ height² (inches)
Imperial: BMI = 703 × weight (lbs) ÷ height² (inches)
Example Calculation
For someone weighing 70 kg and standing 175 cm tall:
Height in meters: 175 cm ÷ 100 = 1.75 m
BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9 (Normal weight)
BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 = 22.9 (Normal weight)
Limitations of BMI
While BMI is a useful screening tool, it has important limitations:
- Muscle mass: Athletes and bodybuilders may show "overweight" BMI despite having low body fat.
- Age variations: BMI thresholds can differ for children, teens, and the elderly.
- Ethnicity: Some populations have different health risks at the same BMI values.
- Fat distribution: BMI doesn't indicate where fat is stored (visceral vs. subcutaneous).
Pro Tip: For a more complete picture, use BMI alongside our Body Fat Calculator and waist circumference measurements.
Healthy BMI Tips
- Aim for a BMI between 18.5–24.9 for lowest cardiovascular disease risk.
- If overweight, even a 5–10% weight reduction significantly improves health markers.
- Combine BMI tracking with regular exercise and a balanced diet.
- Consult your doctor if your BMI is outside the normal range.
⚠️ Medical Disclaimer: BMI is a screening tool, not a diagnostic measure. Consult a qualified healthcare professional for personalized medical advice.