BMI Calculator
Check your Body Mass Index and health status.
What is BMI Calculator?
A BMI (Body Mass Index) Calculator computes your BMI — a numerical value derived from your height and weight that provides a quick screening indicator of body weight relative to height. Developed in the 1830s by Belgian mathematician Adolphe Quetelet and later adopted by the World Health Organization, BMI is the most widely used initial assessment tool for weight status in clinical settings worldwide.
BMI is calculated as weight in kilograms divided by height in meters squared (kg/m²), or using an imperial formula for pounds and inches. The WHO classifies results into four categories: underweight (below 18.5), normal weight (18.5–24.9), overweight (25.0–29.9), and obese (30.0 and above). Within obesity, further subcategories identify Class I (30–34.9), Class II (35–39.9), and Class III (40+) obesity for clinical risk stratification.
While BMI is a useful screening tool used by doctors, insurers, fitness professionals, and public health researchers, it has well-documented limitations — it does not distinguish between muscle and fat mass, does not account for fat distribution (visceral vs. subcutaneous), and uses different healthy ranges for different ethnic populations. The calculator should be used alongside other health metrics, not as a standalone diagnosis.
How to Use BMI Calculator
- 1Step 1: Select your preferred unit system — metric (kilograms and centimeters) or imperial (pounds and feet/inches) — to match how you know your measurements.
- 2Step 2: Enter your height accurately. Remove shoes for measurement and stand straight against a wall for the most accurate reading.
- 3Step 3: Enter your current body weight. Weigh yourself at the same time each day (morning, after using the bathroom) for consistency.
- 4Step 4: Click Calculate to see your BMI value and which WHO category it falls into — underweight, normal weight, overweight, or one of the obesity classes.
- 5Step 5: Review the healthy BMI range for your height and, if outside the normal range, note how many kilograms or pounds would bring you into the healthy category.
Benefits of Using BMI Calculator
- ✓Universal Health Screening: BMI is the global standard for initial weight status screening used by healthcare providers, enabling consistent communication between patients and clinicians.
- ✓Trend Tracking: Track your BMI over weeks and months to measure progress toward weight loss or gain goals with a standardized, reproducible metric.
- ✓Risk Awareness: Higher BMI is statistically associated with increased risk of type 2 diabetes, cardiovascular disease, and certain cancers — knowing your number motivates health action.
- ✓Instant Calculation: Get your BMI in seconds without any specialized equipment — just your height and weight and this free tool.
- ✓Healthy Weight Range: See the exact weight range that corresponds to a healthy BMI for your height, giving you a concrete target rather than an abstract goal.
- ✓Family Health Monitoring: Parents can track children's BMI using age and sex-specific pediatric BMI charts to monitor healthy growth patterns over time.
Example
About BMI Calculator
BMI Calculator computes your Body Mass Index from height and weight and categorizes the result as underweight, normal, overweight, or obese according to WHO standards. It supports both metric and imperial units. A quick health screening tool for adults.
- Metric and imperial unit support
- WHO BMI category classification
- Instant BMI computation
- Healthy weight range display