BMI Calculator for Adults & Teens

Maintaining a healthy body weight is important for overall wellness. The Body Mass Index (BMI) Calculator helps you understand your weight category relative to your height. BMI is widely used by doctors, nutritionists, and fitness experts to assess whether a person is underweight, normal weight, overweight, or obese.

Why BMI Matters

• Health Awareness: Helps identify potential health risks related to weight.
• Fitness Tracking: Allows adults and teens to monitor changes over time.
• Medical Assessment: Used in routine checkups and growth evaluations for teens.
• Weight Management: Guides diet and exercise planning.

BMI Formula

BMI is calculated differently depending on whether you use metric or imperial units:

• Metric: BMI = weight (kg) ÷ [height (m)]²
• Imperial: BMI = 703 × weight (lb) ÷ [height (in)]²

How the BMI Calculator Works

1. Enter your weight in kilograms (kg) or pounds (lb).
2. Enter your height in meters (m) or inches (in).
3. The calculator applies the formula automatically.
4. Your BMI value is displayed along with your weight category.

Step-by-Step Example 1: Adult (Metric)

Problem: A person weighs 70 kg and is 1.75 meters tall. Calculate BMI.
Formula: BMI = weight ÷ height²
Solution: BMI = 70 ÷ (1.75 × 1.75) = 70 ÷ 3.0625 ≈ 22.86
Category: Normal weight (18.5 – 24.9)

Step-by-Step Example 2: Teen (Imperial)

Problem: A teen weighs 120 lb and is 62 inches tall. Calculate BMI.
Formula: BMI = 703 × weight ÷ height²
Solution: BMI = 703 × 120 ÷ (62 × 62) = 84,360 ÷ 3,844 ≈ 21.95
Category: Healthy weight

BMI Categories (Adults & Teens)

• Underweight: BMI < 18.5
• Normal weight: 18.5 – 24.9
• Overweight: 25 – 29.9
• Obese: BMI ≥ 30

FAQs – BMI Calculator

1. Is BMI accurate for everyone?
BMI is a general guideline. Athletes with high muscle mass may have higher BMI despite low body fat.

2. Can teens use the same BMI ranges as adults?
Teens use BMI-for-age percentiles. The calculator provides age-adjusted interpretation for teens.

3. What units can I use?
You can use metric (kg/m) or imperial (lb/in) units.

4. Does BMI consider body fat percentage?
No, BMI is based on weight and height only. Body composition measurements provide more detail.

5. Can I use BMI to plan my diet?
Yes, it gives a general idea of your weight category and can guide lifestyle changes.

6. Can BMI change over time?
Yes, monitoring BMI over weeks or months helps track progress in weight management.

7. Is BMI suitable for children under 2?
No, BMI is not recommended for infants and toddlers; pediatric growth charts are used instead.

8. How often should I check BMI?
Adults and teens can check BMI periodically, such as monthly or quarterly.

9. Can BMI predict health risks?
It provides a general indicator of potential risks like heart disease or diabetes.

10. Is this BMI calculator free to use?
Yes, it is completely free and works on any modern browser.