Calculators logocalculators.so

BMI Calculator

BMI calculator to calculate your Body Mass Index and understand what it means for your health.

BMI calculator

A BMI calculator is a practical tool that allows you to quickly and easily calculate your Body Mass Index (BMI). It's a useful indicator to assess whether your weight is appropriate for your height and to understand potential health risks associated with your weight.

Easily and quickly calculate your BMI using the BMI calculator by simply entering your height and weight. The calculator supports both metric (centimeters/kilograms) and imperial (inches/pounds) units, and will provide you with your BMI value, ideal weight range, and interpret what it means for your health.

Table of contents

What is BMI?

Body Mass Index (BMI) is a simple calculation that uses your height and weight to work out if your weight is healthy. The BMI calculation divides an adult's weight in kilograms by their height in metres squared (kg/m²).

BMI is a useful tool for:

  • Health screening: Identifying potential weight-related health risks
  • Fitness goals: Setting realistic weight targets
  • Medical assessment: Healthcare professionals use BMI as a screening tool
  • Population studies: Understanding weight trends in different populations

How to use the BMI calculator

The BMI calculator is easy to use and supports both metric and imperial units.

Steps to use:

  1. Choose your unit system: Select between metric (cm/kg) or imperial (in/lbs)
  2. Enter your height: Input your height in the selected unit system
    • Metric: Enter height in centimeters (cm)
    • Imperial: Enter height in inches (in)
  3. Enter your weight: Input your weight in the selected unit system
    • Metric: Enter weight in kilograms (kg)
    • Imperial: Enter weight in pounds (lbs)
  4. Get your result: Your BMI, health category, and ideal weight range will display automatically

The calculator will show your BMI value, ideal weight range for your height, and interpret what it means for your health.

Unit system support

The BMI calculator supports two unit systems:

Metric system (cm/kg)

  • Height: Enter in centimeters (cm)
  • Weight: Enter in kilograms (kg)
  • Example: 170 cm height, 65 kg weight

Imperial system (in/lbs)

  • Height: Enter in inches (in)
  • Weight: Enter in pounds (lbs)
  • Example: 67 in height, 150 lbs weight

The calculator automatically converts between units and provides results in your chosen system.

BMI categories and health implications

The World Health Organization (WHO) defines the following BMI categories:

BMI RangeCategoryHealth Status
< 18.5UnderweightBelow healthy weight range
18.5 - 24.9Normal WeightHealthy weight range
25.0 - 29.9OverweightAbove healthy weight range
30.0 - 34.9Obesity Class IModerately obese
35.0 - 39.9Obesity Class IISeverely obese
≥ 40.0Obesity Class IIIVery severely obese

Underweight (BMI < 18.5)

  • Health implications: May indicate malnutrition, eating disorders, or other health conditions
  • Recommendations: Consult a healthcare professional if unintentional weight loss occurs

Normal Weight (BMI 18.5 - 24.9)

  • Health implications: Generally associated with good health
  • Recommendations: Maintain healthy lifestyle habits

Overweight (BMI 25 - 29.9)

  • Health implications: Increased risk of health problems
  • Recommendations: Consider lifestyle changes to prevent further weight gain

Obesity Class I (BMI 30 - 34.9)

  • Health implications: Higher risk of heart disease, diabetes, and other conditions
  • Recommendations: Medical consultation recommended for weight management

Obesity Class II (BMI 35 - 39.9)

  • Health implications: Significantly increased health risks
  • Recommendations: Medical intervention often necessary

Obesity Class III (BMI ≥ 40)

  • Health implications: Severe health risks requiring medical attention
  • Recommendations: Immediate medical consultation recommended

How to calculate BMI

The BMI formula is simple:

BMI = weight (kg) / height (m)²

Example (Metric): If you weigh 70 kg and are 1.75 m tall:

  • BMI = 70 / (1.75 × 1.75) = 70 / 3.0625 = 22.9

Example (Imperial): If you weigh 154 lbs and are 69 in tall:

  • Convert to metric: 154 lbs = 69.9 kg, 69 in = 1.75 m
  • BMI = 69.9 / (1.75 × 1.75) = 69.9 / 3.0625 = 22.9

Ideal weight range

The calculator also provides your ideal weight range based on the healthy BMI range (18.5-24.9) for your height. This range represents the weight that is considered healthy for someone of your height.

Limitations of BMI

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

  • Muscle mass: Athletes with high muscle mass may have high BMI despite being healthy
  • Age: BMI categories may not be appropriate for older adults
  • Ethnicity: Different ethnic groups may have different healthy BMI ranges
  • Body composition: BMI doesn't distinguish between fat and muscle mass
  • Children: Different BMI charts are used for children and adolescents

When to consult a healthcare professional

Consider consulting a healthcare professional if:

  • Your BMI falls outside the normal range
  • You have concerns about your weight
  • You're experiencing unexplained weight changes
  • You have other health conditions that may affect your weight

BMI and Health

BMI is just one indicator of health. Other important factors include:

  • Physical activity: Regular exercise is crucial for health
  • Diet: Balanced nutrition is essential
  • Medical history: Family history and existing conditions matter
  • Lifestyle factors: Sleep, stress, and other lifestyle choices affect health

Useful links and resources