What is BMI?

BMI (Body Mass Index) is a measure of body fat based on your weight and height. It's used worldwide as a quick screening tool to categorize adults into underweight, normal weight, overweight, or obese. BMI doesn't measure body fat directly, but it correlates well with more direct measures.

BMI Formula

BMI = Weight (kg) ÷ Height (m)²

Example: Weight 70 kg, Height 1.70 m → BMI = 70 ÷ (1.70 × 1.70) = 24.2

BMI Categories (WHO)

• Below 18.5 — Underweight
• 18.5 – 24.9 — Normal weight
• 25.0 – 29.9 — Overweight
• 30.0 and above — Obese

Limitations of BMI

BMI has some limitations you should know:

• Doesn't distinguish between muscle and fat — athletes may show "overweight"
• Doesn't account for age, gender, or body composition
• Not accurate for pregnant women
• Not suitable for children (use BMI-for-age percentile)

What to Do With Your BMI

If your BMI is outside the normal range, don't panic. BMI is just a screening tool. Consult a doctor or nutritionist for a full assessment. Lifestyle factors like diet, exercise, sleep, and stress matter just as much.

Why Use Our BMI Calculator?

Our free BMI calculator gives you instant results with category classification. Track your BMI over time as you work towards health goals. Works on all devices, no signup required.