BMI Calculator - Free Body Mass Index Tool | Hexa

Understanding Body Mass Index (BMI)

Body Mass Index (BMI) is a widely used screening tool that relates your weight to your height. The formula is simple: weight in kilograms divided by height in meters squared. A BMI of 22 means you're in the middle of the "normal" range for your height. Doctors, insurers, and researchers use BMI as a first-step indicator of weight-related health risks. It's not a perfect measure—it doesn't distinguish muscle from fat or account for age, sex, or bone structure—but it's a quick, free way to see where you stand. The World Health Organization (WHO) and CDC use BMI categories to track obesity trends and guide public health. For authoritative information, see WHO Obesity and overweight, CDC BMI, and NIH BMI Calculator.

BMI Categories Explained

Underweight (below 18.5): May indicate inadequate nutrition, eating disorders, or other health issues. Consult a healthcare provider if you're concerned.

Normal (18.5–24.9): Associated with lower risk of weight-related conditions. This range is considered healthy for most adults.

Overweight (25–29.9): Increased risk of cardiovascular disease, diabetes, and other conditions. Many people in this range can benefit from lifestyle changes.

Obese (30+): Higher risk of serious health problems. Medical guidance is recommended for sustainable weight management.

These categories are screening tools, not diagnoses. Always consult a doctor for personalized advice.

When BMI Can Be Misleading

BMI doesn't distinguish muscle from fat. A bodybuilder with low body fat may have a BMI in the "overweight" range because muscle weighs more than fat. Similarly, older adults may have "normal" BMI but carry excess visceral fat. Athletes, pregnant women, and people with certain medical conditions should interpret BMI with caution. Use it as one indicator among many—not the sole measure of health.

Privacy and How Our Calculator Works

All calculations run locally in your browser. We never see, store, or transmit your weight, height, or results. Enter your values and get your BMI and category instantly. No signup, no account—just a quick, private check.

Open the BMI calculator below. Enter your weight (kg) and height (cm) to get your BMI and category. Use it to track fitness progress, prepare for a checkup, or satisfy curiosity—all in seconds.