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BMI Calculator

Body Mass Index (BMI) is a widely used screening method to categorize weight status. This BMI calculator allows you to input your weight and height to determine if you fall into the underweight, normal weight, overweight, or obese category. While BMI is not a perfect measure of health as it does not account for muscle mass, it serves as a useful starting point for understanding your general body composition.

How this calculator works

This calculator performs the standard Body Mass Index calculation instantly:

  1. It takes your weight in kilograms.
  2. It squares your height in meters.
  3. It divides the weight by the squared height.
  4. It compares the result against WHO health categories.

BMI Categories and Formula Explained

The Body Mass Index is calculated using the formula: BMI = kg / m². The resulting score places you into one of the following standard categories:

  • Underweight: BMI less than 18.5
  • Normal weight: BMI between 18.5 and 24.9
  • Overweight: BMI between 25 and 29.9
  • Obesity: BMI of 30 or greater

Limitations of BMI

While BMI is a useful screening tool, it does not diagnose body fatness or health directly. It has limitations because it does not distinguish between weight from muscle and weight from fat.

  • Athletes: May have a high BMI due to increased muscle mass, not body fat.
  • Age: Older adults may have more body fat than younger adults with the same BMI.
  • Bone Density: Variations in bone structure and density can affect weight.

Common Uses

  • Health Screening: Quickly identifying potential weight-related health risks for adults.
  • Fitness Tracking: Monitoring general body composition changes over time during diet or exercise programs.
  • Medical Assessment: Used by healthcare professionals as a preliminary indicator of metabolic health.

Examples

  • Healthy Weight: A person weighing 70kg at 175cm height has a BMI of 22.9, which falls within the Normal range.
  • Overweight: A person weighing 90kg at the same 175cm height has a BMI of 29.4, categorized as Overweight.

? Frequently Asked Questions

A healthy BMI typically ranges from 18.5 to 24.9 for most adults.

Yes, BMI does not distinguish between muscle and fat. Highly active individuals or athletes may have a high BMI despite having low body fat.

BMI for children and teens needs to be interpreted differently, using age and gender-specific percentiles, rather than these adult categories.