BMI Calculator - Body Mass Index

Your BMI

📖 How to Use

1
Select your preferred unit system — Metric (kg/cm) or Imperial (lbs/inches).
2
Enter your weight in the first field.
3
Enter your height in the second field.
4
Click Calculate BMI — see your BMI value and category instantly.

📐 Formula

BMI = weight (kg) ÷ height² (m)

The BMI formula divides your weight in kilograms by the square of your height in meters. For imperial units, the formula is: BMI = (weight (lbs) ÷ height² (in)) × 703

< 18.5

Underweight

18.5 – 24.9

Normal

25 – 29.9

Overweight

≥ 30

Obese

💡 Examples

Example 1 — Normal Weight

Weight: 70 kg, Height: 175 cm

BMI = 70 ÷ (1.75)² = 22.9 → Normal weight ✓

Example 2 — Overweight

Weight: 90 kg, Height: 170 cm

BMI = 90 ÷ (1.70)² = 31.1 → Obese ⚠️

Example 3 — Imperial

Weight: 154 lbs, Height: 67 inches (5'7")

BMI = (154 ÷ 67²) × 703 = 24.1 → Normal weight ✓

❓ FAQ

BMI is a useful screening tool but not a diagnostic measure. It doesn't account for muscle mass, bone density, age, or gender. Athletes may have a high BMI due to muscle, not fat. Always consult a healthcare provider for a complete health assessment.

For most adults, a BMI between 18.5 and 24.9 is considered normal/healthy. A BMI below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is classified as obese. For children and teens, BMI is age and sex-specific.

The BMI formula is the same for men and women, but healthy body fat percentages differ. Women naturally have more body fat than men. Some health professionals use additional measurements like waist circumference alongside BMI.