BMI Calculator – Body Mass Index (Metric & Imperial)
BMI Calculator
Calcon's free BMI Calculator instantly computes your Body Mass Index from your height and weight. Switch between metric (kg and cm) or imperial (lbs, feet, and inches) inputs. Results include your BMI value, category, and a visual scale showing where you fall.
BMI Formula
Metric Formula
BMI = weight(kg) / height(m)²
Example: 70 kg, 175 cm (1.75 m)
BMI = 70 / (1.75 × 1.75) = 70 / 3.0625 = 22.9
Imperial Formula
BMI = (weight(lbs) × 703) / height(in)²
Example: 154 lbs, 5'9" (69 in)
BMI = (154 × 703) / (69 × 69) = 108,262 / 4,761 = 22.7
BMI Categories (WHO)
| BMI Range | Category | Health Risk |
|---|---|---|
| < 18.5 | Underweight | Malnutrition risk |
| 18.5 – 24.9 | Normal weight | Low risk |
| 25 – 29.9 | Overweight | Enhanced risk |
| ≥ 30 | Obese | High to very high risk |
Frequently Asked Questions
What is BMI and how is it calculated?
BMI (Body Mass Index) is a number derived from your height and weight used to estimate body fat. Metric: BMI = weight(kg) / height(m)². Imperial: BMI = (weight(lbs) × 703) / height(inches)². It is a screening tool used by healthcare providers worldwide.
What is a healthy BMI?
According to the World Health Organization (WHO), a healthy BMI for adults is 18.5 to 24.9. BMI below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese.
Is BMI accurate for everyone?
BMI is a useful population-level screening tool but has limitations for individuals. It does not account for muscle mass (athletes often have a high BMI due to muscle, not fat), bone density, age, sex, or ethnicity. Always consult a healthcare provider for a comprehensive health evaluation.
What BMI is considered obese?
A BMI of 30 or above is classified as obese by the WHO. This is further divided into Class 1 obesity (30–34.9), Class 2 (35–39.9), and Class 3 or severe obesity (40 and above). Obesity is associated with increased risk of diabetes, heart disease, and other health conditions.
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