BMI Calculator

Calculate your Body Mass Index (BMI) with our free BMI Calculator. Determine if your weight is in the healthy range based on your height.

Unit System
Enter your weight in kilograms
Enter your height in centimeters
Display Options
Widget
Related Tools
Calories Burned Sleeping Calculator Dog Age Calculator

What is a BMI Calculator?

A BMI (Body Mass Index) Calculator is a tool that estimates body fat based on a person's weight and height. It's a widely used screening tool that helps categorize individuals as underweight, normal weight, overweight, or obese. While BMI doesn't directly measure body fat, it provides a reasonable indicator of body fatness for most people and is used to screen for potential weight-related health problems.

Understanding BMI Calculation

BMI is calculated using simple formulas that vary based on the unit system:

  • Metric Formula: BMI = weight(kg) / height(m)²
  • Imperial Formula: BMI = 703 × weight(lb) / height(in)²

The resulting value is then categorized into different weight status groups:

  • Below 18.5: Underweight
  • 18.5 - 24.9: Normal weight
  • 25.0 - 29.9: Overweight
  • 30.0 and above: Obese

BMI Categories in Detail

BMI categories can be further refined for more detailed assessment:

  • Severe Thinness: BMI less than 16
  • Moderate Thinness: BMI between 16 and 17
  • Mild Thinness: BMI between 17 and 18.5
  • Normal: BMI between 18.5 and 25
  • Overweight: BMI between 25 and 30
  • Obese Class I: BMI between 30 and 35
  • Obese Class II: BMI between 35 and 40
  • Obese Class III: BMI of 40 or higher

Limitations of BMI

While BMI is a useful screening tool, it has several limitations:

  • Muscle Mass: BMI doesn't distinguish between muscle and fat. Athletes with high muscle mass may have a high BMI despite having healthy body fat levels.
  • Body Composition: It doesn't account for differences in bone density, muscle mass, or fat distribution.
  • Age and Sex: BMI doesn't consider age-related changes in body composition or differences between men and women.
  • Ethnic Variations: Different ethnic groups may have different body compositions at the same BMI level.

Health Implications of BMI Categories

Different BMI categories are associated with varying health risks:

  • Underweight: May indicate malnutrition, eating disorders, or other health problems.
  • Normal weight: Generally associated with the lowest health risks for most people.
  • Overweight: May increase the risk of heart disease, type 2 diabetes, and certain cancers.
  • Obese: Higher risk of serious health conditions including cardiovascular disease, stroke, type 2 diabetes, sleep apnea, and certain cancers.

Using Our BMI Calculator

Our calculator offers comprehensive BMI analysis with these simple steps:

  1. Select your preferred unit system (metric or imperial)
  2. Enter your weight (in kilograms or pounds)
  3. Enter your height (in centimeters or feet/inches)
  4. Choose display options for formula, BMI categories, and health information
  5. Get instant results showing your BMI, category, and personalized health information

The calculator provides color-coded results for easy interpretation and includes detailed information about BMI categories and health implications to help you better understand your results.