What is the BMI Calculator?
The Body Mass Index (BMI) Calculator is a screening tool used worldwide to evaluate a person's weight status in relation to their height. Originally known as the Quetelet Index, it provides a simple numeric value that categorizes individuals into groups: Underweight, Normal Weight, Overweight, or Obese.
While it is not a direct measurement of body fat percentage, BMI is a reliable indicator for most adults to assess potential health risks associated with weight, such as heart disease, high blood pressure, and type 2 diabetes.
Key Features
Dual Unit Support
Calculate using Metric (kg/cm) or Imperial (lbs/feet) systems.
Instant Results
Get your BMI score and category immediately without page reloads.
Privacy First
Calculations happen in your browser. No personal health data is stored.
WHO Standards
Classifications based on official World Health Organization guidelines.
How to Use This Tool
Checking your Body Mass Index is simple. Follow these 3 steps to get an accurate reading:
Select Units
Toggle between Metric (Kilograms/Centimeters) or Standard (Pounds/Feet & Inches) depending on your preference.
Enter Details
Input your accurate height and current weight. For the most precise result, weigh yourself in the morning.
See Category
The tool will highlight your BMI score and tell you if you fall into the Underweight, Healthy, or Overweight range.
Understanding Your BMI
The Science Behind the Number
The BMI formula is defined as the body mass divided by the square of the body height. It is expressed in units of kg/m². This universal standard allows health professionals to discuss weight issues objectively.
However, it is important to treat BMI as a "Screening Tool" rather than a diagnostic one. A high BMI indicates high body fatness for most people, but it does not measure body fat directly.
BMI Categories Chart (WHO)
| Classification | BMI Range (kg/m²) |
|---|---|
| Underweight | < 18.5 |
| Normal Weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obesity (Class I) | 30.0 – 34.9 |
| Obesity (Class II) | 35.0 – 39.9 |
Important Limitations
BMI does not distinguish between muscle, bone, and fat.
1. Athletes: May be classified as overweight due to muscle mass.
2. Elderly: May have a "normal" BMI but low muscle mass (sarcopenia).
3. Pregnancy: BMI charts do not apply to pregnant women.
Tips for a Healthy BMI
- • Aim for 150 minutes of moderate activity per week.
- • Focus on nutrient-dense foods (vegetables, lean proteins).
- • Stay hydrated and prioritize sleep (7-9 hours).
- • Avoid crash diets; aim for sustainable lifestyle changes.