BMI 계산기

What is BMI?

Body Mass Index (BMI) is a simple calculation using your height and weight to estimate body fat. Developed by Belgian mathematician Adolphe Quetelet in the 1830s, BMI has become the most widely used screening tool for categorizing weight status in adults. It provides a quick, cost-free way to identify potential weight-related health risks.

The BMI Formula

BMI is calculated using the formula:

BMI = Weight (kg) ÷ Height² (m²)

Or in imperial units:

BMI = (Weight (lbs) × 703) ÷ Height² (inches²)

For example, a person who is 5'9" (69 inches) and weighs 165 lbs has a BMI of: (165 × 703) ÷ (69²) = 24.4

BMI Categories Explained

The World Health Organization defines these BMI categories for adults:

• Severe Underweight: BMI below 16.0 – High risk of malnutrition
• Underweight: BMI 16.0 to 18.4 – May indicate nutritional deficiencies
• Normal Weight: BMI 18.5 to 24.9 – Optimal range for most adults
• Overweight: BMI 25.0 to 29.9 – Increased health risks
• Obese Class I: BMI 30.0 to 34.9 – Moderate obesity
• Obese Class II: BMI 35.0 to 39.9 – Severe obesity
• Obese Class III: BMI 40.0 and above – Very severe (morbid) obesity

Real-World Examples

• 5'4" (163 cm), 130 lbs (59 kg): BMI = 22.3 (Normal)
• 5'9" (175 cm), 165 lbs (75 kg): BMI = 24.4 (Normal)
• 6'0" (183 cm), 200 lbs (91 kg): BMI = 27.1 (Overweight)
• 5'6" (168 cm), 180 lbs (82 kg): BMI = 29.1 (Overweight)
• 5'10" (178 cm), 220 lbs (100 kg): BMI = 31.6 (Obese Class I)

Health Risks by BMI Category

Research shows that both very low and high BMI are associated with increased health risks:

• Underweight: Weakened immune system, osteoporosis, fertility issues, anemia
• Normal: Lower risk of chronic diseases, optimal metabolic function
• Overweight/Obese: Type 2 diabetes, cardiovascular disease, hypertension, sleep apnea, certain cancers, joint problems

Limitations of BMI

While BMI is a useful screening tool, it has important limitations:

• Muscle vs. Fat: Athletes and muscular individuals may have high BMI despite low body fat
• Age: Elderly individuals may have normal BMI but high body fat due to muscle loss
• Gender: Women typically have more body fat than men at the same BMI
• Ethnicity: Health risks may occur at different BMI thresholds for different populations
• Fat Distribution: BMI doesn't account for where fat is stored (belly fat is more dangerous)

Beyond BMI: Complete Body Assessment

For a more complete picture of your health, combine BMI with these tools:

• Body Fat Calculator – Estimate your body fat percentage
• Calorie Calculator – Determine your daily energy needs
• Waist-to-Hip Ratio – Measures fat distribution (waist ÷ hip circumference)
• Waist Circumference – Men >40", women >35" indicates elevated risk

About Our Calculations

Our BMI calculator uses the standard World Health Organization formula. Results are calculated instantly as you type and are accurate to one decimal place. For adults 20 years and older, we use the standard adult BMI categories. Children and teens require age-specific BMI percentile charts not covered by this calculator. Always consult a healthcare provider for personalized medical advice.