BMI Calculator: A Complete Guide
What is BMI?
Body Mass Index (BMI) is a simple screening tool that estimates body fat based on your height and weight. Use our BMI Calculator to check your category and learn what it means for your health.
1. How to Calculate Your BMI
The Formula
BMI = weight (kg) ÷ height² (m²)
Or: [weight (lbs) ÷ height² (in²)] × 703
Step-by-Step
Measure Accurately
Weigh yourself in kilograms (or pounds) and measure height in meters (or inches).
Use Our Calculator
Enter your data into the BMI Calculator (no math needed!).
Interpret Results
Compare your score to the standard categories below.
Try It Yourself
Example Calculation
For a person who is 1.75m (5'9") tall and weighs 68kg (150lbs):
68 ÷ (1.75 × 1.75) = 22.2 (Normal weight)
Calculate Your BMI Now →2. BMI Categories
| BMI Range | Category | Health Risk |
|---|---|---|
| Below 18.5 | Underweight | Nutritional deficiency, osteoporosis |
| 18.5 – 24.9 | Normal weight | Low risk |
| 25.0 – 29.9 | Overweight | Moderate risk |
| 30.0 and above | Obese | High risk |
⚠️ Important Notes
- BMI doesn't account for muscle mass (athletes may score higher).
- Not suitable for children (use CDC's pediatric calculator).
3. Practice Problems
Calculate BMI
A patient weighs 85kg and is 1.8m tall. What's their BMI category?
85 ÷ (1.8 × 1.8) = 26.2 → Overweight
Convert Units
Calculate BMI for someone who is 5'4" (64 inches) and weighs 140 pounds. (Hint: Use the imperial formula)
[140 ÷ (64 × 64)] × 703 = 24.0 → Normal weight