ClickCrowd ToolsBMI Calculator
Calculate your Body Mass Index instantly using metric or imperial units.
⚠️ Important: This calculator is for general informational purposes only and does not provide a medical diagnosis. BMI does not account for muscle mass, bone density, overall body composition, or racial and sex differences. Always consult a qualified health professional for any questions about your health, weight or treatment.
How to use this tool
- •Select metric or imperial units.
- •Enter your height and weight in the corresponding fields.
- •Click the "Calculate BMI" button.
- •View your BMI value and category instantly.
- •Adjust your inputs if you need to calculate again.
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What Is BMI? (Body Mass Index Explained)
Body Mass Index (BMI) is a standardized measurement that uses your height and weight to estimate whether you are underweight, at a healthy weight, overweight or obese. It is one of the most widely used health indicators worldwide due to its simplicity and consistency. While BMI is not a medical diagnosis, it provides a useful snapshot of your general health status.
How BMI Is Calculated
BMI Formula (Metric System)
BMI = weight (kg) / height² (m²)
BMI Formula (Imperial System)
BMI = (weight in lbs / height in inches²) × 703
Our BMI Calculator automatically applies the correct formula depending on whether you select metric or imperial units.
BMI Chart — Categories and Weight Ranges
| BMI Range | Weight Category |
|---|---|
| Below 18.5 | Underweight |
| 18.5 – 24.9 | Healthy / Normal Weight |
| 25 – 29.9 | Overweight |
| 30 – 34.9 | Obesity Class I |
| 35 – 39.9 | Obesity Class II |
| 40+ | Obesity Class III |
These ranges help you understand where your BMI falls relative to general population guidelines.
How Age and Gender Affect BMI
Gender Differences
Women naturally carry more body fat than men, meaning two people with the same BMI may have different body compositions.
Age Differences
As people age, muscle mass tends to decrease while fat mass increases. Older adults may fall into slightly higher BMI ranges while still maintaining good overall health.
Metric vs Imperial BMI — Choosing Your Measurement System
Our BMI Calculator supports both metric (centimeters and kilograms) and imperial (feet, inches and pounds) systems. Regardless of the system you choose, the resulting BMI and weight category remain consistent.
Limitations of BMI You Should Know
Although BMI is a useful screening tool, it does not measure body fat percentage, muscle mass, bone density, fat distribution, or metabolic health. For example, athletes may have a high BMI due to muscle mass, not excess fat. BMI may also be inaccurate for pregnant women, elderly individuals, children, or people with certain medical conditions.
When Should You Consult a Health Professional?
If your BMI falls outside the healthy range or if you experience health concerns, consulting a healthcare provider is recommended. A professional assessment can include body fat percentage, waist circumference, blood pressure, blood tests and lifestyle evaluation. BMI should always be considered as one component of your overall health picture.