BMI Calculator

Calculate Body Mass Index (BMI) with instant health category categorization and ideal weight range.

BMI Calculator

WHO standard Body Mass Index & Healthy Weight assessment

Frequently Asked Questions

What are the standard WHO BMI categories?▼

Underweight: BMI less than 18.5; Normal / Healthy Weight: BMI 18.5 to 24.9; Overweight: BMI 25.0 to 29.9; Obesity Class I: BMI 30.0 to 34.9; Obesity Class II: BMI 35.0 to 39.9; Obesity Class III: BMI 40.0 or higher.

Is BMI accurate for muscular individuals or athletes?▼

BMI does not differentiate between lean muscle mass and adipose fat tissue. Bodybuilders and strength athletes often register in the overweight or obese ranges despite having low body fat percentages. For these individuals, skinfold calipers or DEXA scans are more informative.

What is the healthy weight range for my height?▼

A healthy weight corresponds to a BMI between 18.5 and 24.9. Our calculator automatically computes your customized lower and upper weight thresholds based on your exact height.

Does the BMI formula change for men vs women?▼

The mathematical formula for standard adult BMI is identical for both men and women. However, women typically have higher percentages of body fat than men at the same BMI reading.

How often should I check my BMI?▼

Checking once a month or during quarterly health reviews is recommended. Daily fluctuations in weight are primarily water balance and digestive shifts rather than meaningful changes in body composition.

Expert Tips

BMI is a screening tool, not a direct diagnostic measure of body fat percentage or cardiovascular fitness.
Athletes with high muscle mass may record elevated BMIs despite low body fat levels.
Combine your BMI reading with waist-to-hip ratio and clinical blood panels for a comprehensive health picture.

Overview & Application

Body Mass Index (BMI) is an internationally recognized anthropometric screening metric endorsed by the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). It correlates an individual's mass and height to categorize body composition into underweight, normal weight, overweight, and obesity classes. This BMI Calculator supports both Metric (centimeters & kilograms) and Imperial (feet, inches & pounds) systems with instant visual status feedback.

How to Use the BMI Calculator

Choose your preferred unit system: Metric (cm / kg) or Imperial (feet / inches / lbs).
Enter your height and current body weight.
Optionally select your gender and age for contextual guidance.
Click 'Calculate BMI' to see your exact index score.
Examine the color-coded health gauge and recommended ideal weight range for your height.

Standard World Health Organization BMI Formula

BMI is defined as a person's weight in kilograms divided by the square of their height in meters. In imperial units, weight in pounds is divided by height in inches squared, multiplied by the conversion factor 703.

Metric: BMI = Weight (kg) / [Height (m)]² Imperial: BMI = [Weight (lbs) × 703] / [Height (inches)]² Healthy Weight Range = 18.5 × [Height (m)]² to 24.9 × [Height (m)]²