Body Mass Index (BMI)

Screening index for weight status using height and weight.

BMI = weight / height²

Patient parameters

Adjust values, then click Calculate.

Height (cm)

30–250

Weight (kg)

1–300

Results

BMI: 24.2

What this calculator does

Body mass index (BMI) is a widely used screening measure that relates body weight to height. It helps categorize underweight, healthy weight, overweight, and obesity for adults in population health and clinic settings.

Formula and variables

Displayed formula: BMI = weight / height²

The engine evaluates: BMI. Variable names match the input field keys so you can trace each step from entry to output.

How to use this tool

1. Open the Body Mass Index (BMI) and enter your values using the units shown beside each field.
2. Review that inputs are within the typical physiological range before you calculate.
3. Read the result together with the interpretation notes below and your local clinical context.

How to interpret the result

For adults, BMI below 18.5 may suggest underweight; 18.5–24.9 is often considered a healthy range; 25–29.9 indicates overweight; 30 and above indicates obesity. BMI does not distinguish muscle from fat and may misclassify athletes, older adults, and some ethnic groups—use it alongside waist measures and clinical context.

Clinical context

In pregnancy, pediatrics, and certain chronic diseases, prefer specialty growth charts or alternative indices rather than adult BMI categories alone.

Limitations and disclaimer

This tool supports education and clinical triage only. It does not replace professional medical advice, diagnosis, or treatment. Reference ranges vary by laboratory, age, pregnancy status, and comorbidity. Always confirm critical decisions with institutional protocols and qualified clinicians.

Common questions

**Is BMI accurate for everyone?**
No. It is a population screening tool. Muscular builds, edema, and age-related body composition changes can shift interpretation.

**Should I use BMI alone to diagnose obesity?**
Clinical diagnosis considers exam findings, metabolic risk, waist circumference, and comorbidities—not BMI by itself.