Calculate your Body Mass Index and understand your health category with our free online tool
Calculate BMI using either metric (kg/cm) or imperial (lbs/ft-in) units. Easily switch between systems based on your preference.
Interactive color-coded scale shows your BMI position across categories: underweight, normal, overweight, and obese.
Real-time BMI calculation as you type. See your results immediately with detailed health category information.
Get personalized health information based on your BMI category, including potential health risks and recommendations.
Easy-to-understand visual indicators help you quickly identify your health category at a glance.
All calculations happen in your browser. Your health data never leaves your device and is never stored or transmitted.
BMI (Body Mass Index) is a measure of body fat based on height and weight. It's calculated as weight in kilograms divided by height in meters squared (kg/m²). BMI is used to categorize individuals as underweight, normal weight, overweight, or obese.
BMI = weight (kg) / height² (m²). For imperial units: BMI = (weight (lbs) / height² (inches²)) × 703. For example, a person weighing 70 kg and 1.75m tall has a BMI of 70 / (1.75 × 1.75) = 22.86.
A healthy BMI for adults is typically between 18.5 and 24.9. Below 18.5 is underweight, 25-29.9 is overweight, and 30+ is obese. However, BMI is just one indicator and doesn't account for muscle mass or body composition.
BMI has limitations. It doesn't distinguish between muscle and fat, so athletes may have high BMI despite being healthy. It may also not be accurate for elderly individuals, pregnant women, or certain ethnic groups. Consult a healthcare provider for personalized assessment.
BMI categories for adults: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obese Class I (30-34.9), Obese Class II (35-39.9), Obese Class III (≥40).
Athletes often have higher muscle mass, which weighs more than fat. Since BMI only considers weight and height, a muscular athlete might be classified as overweight or obese when they're actually very fit. Body composition analysis is more accurate for athletes.
For general health monitoring, checking your BMI every few months is sufficient. If you're actively working on weight management or fitness goals, monthly calculations can help track progress. Always combine BMI with other health metrics.
This calculator is designed for adults (18+). Children and teens need age and sex-specific BMI percentiles because their body composition changes as they grow. Consult a pediatrician for accurate BMI assessment for children.