BMI Calculator
Check your body mass index (BMI) and weight status.
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Overview
Body Mass Index (BMI) is calculated by dividing weight (kg) by height (m) squared. It is a widely used international standard for screening overweight and obesity. According to WHO standards, a BMI below 18.5 is underweight, 18.5-24.9 is normal, 25-29.9 is overweight, and 30 or above is obese. BMI is the most widely used obesity screening tool worldwide, allowing you to quickly assess your body weight status with just height and weight inputs. However, BMI cannot distinguish between fat and muscle mass, so it may be less accurate for athletes or muscular individuals. Asians, including Koreans, tend to have higher body fat percentages and more visceral fat at the same BMI compared to Western populations. The WHO Asia-Pacific guidelines therefore apply a lower overweight threshold of BMI 23. Regular BMI monitoring is a first step toward health management, best combined with body fat percentage and waist circumference measurements.
Formula
BMI = weight (kg) / height (m)² | Example: 70 kg, 175 cm → BMI = 70 / 1.75² = 70 / 3.0625 ≈ 22.86 (Normal range)
How to Use
- 1Enter your weight in kilograms.
- 2Enter your height in centimeters (automatically converted to meters).
- 3Click the 'Calculate' button.
- 4Review your BMI value and the corresponding weight classification.
Examples
Adult Male: 70kg / 175cm
Calculate BMI for an average-built adult male.
Adult Female: 55kg / 160cm
Calculate BMI for a typical adult female.
Overweight Assessment: 90kg / 180cm
Evaluate a case that falls into the overweight/obese range.
Background
BMI was devised in 1832 by Belgian mathematician and statistician Adolphe Quetelet as part of his research on human body proportions. Originally called the 'Quetelet Index,' it was renamed 'Body Mass Index' in 1972 by American nutritionist Ancel Keys. The WHO officially adopted BMI as the international standard for obesity classification in 1995, and in 2000 published separate Asia-Pacific cutoffs reflecting the higher body fat characteristics of Asian populations. With nearly 200 years of history, BMI remains the primary screening tool for weight-related health assessments worldwide.
Tips
- ✔BMI may overestimate body fat in muscular individuals such as athletes.
- ✔The Asia-Pacific BMI cutoffs differ from Western standards; overweight starts at BMI 23 for Asian populations.
- ✔BMI alone is not a comprehensive health indicator — consider body fat percentage and waist circumference as well.
- ✔This calculator is for informational purposes only. Consult a healthcare professional for an accurate health assessment.
FAQ
Q. My BMI is normal but I have belly fat. Should I be concerned?
Yes. A normal BMI does not rule out excess visceral fat, which increases metabolic disease risk. Measure your waist circumference (risk thresholds: men ≥ 90 cm, women ≥ 85 cm in Asian populations) and consider a body fat assessment.
Q. Can the same BMI standards be used for children?
No. For children and adolescents under 18, age- and sex-specific BMI percentiles are used. Please use the 'Children BMI Calculator'.
Q. What is the difference between BMI and body fat percentage?
BMI is simply a ratio of weight to height, whereas body fat percentage measures the proportion of fat in total body weight. Body fat percentage provides a more precise health indicator.
Q. Are Asian BMI standards different from Western standards?
Yes. The WHO Asia-Pacific guidelines classify BMI 23+ as overweight and 25+ as obese for Asian populations. Western standards use 25 for overweight and 30 for obesity, reflecting different body fat distributions.
Q. Does a high BMI always mean health problems?
Not necessarily. BMI is a screening tool, not a diagnostic one. A comprehensive health assessment should include body fat percentage, blood pressure, blood sugar, cholesterol, and other clinical markers.
Q. Can pregnant women use BMI?
BMI should not be used as an obesity indicator during pregnancy. Pre-pregnancy BMI is used to set appropriate weight gain targets. Consult an obstetrician for personalized guidance.
Q. Are BMI standards the same for elderly individuals?
Research suggests that for adults over 65, a BMI range of 23-27 is associated with the lowest mortality risk. A slightly higher BMI in older adults may actually help prevent sarcopenia (muscle loss).
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