Body Mass Index

BMI Calculator

Calculate your Body Mass Index (BMI) using metric or imperial measurements to understand your weight category and healthy weight targets.

Guide & Overview

About the BMI Calculator

The Body Mass Index (BMI) Calculator is a standardized screening metric established by the World Health Organization (WHO) to categorize individuals by weight status relative to height. It is widely utilized in epidemiology, general healthcare checkups, and personal fitness monitoring.

BMI is calculated by dividing body weight in kilograms by height in meters squared. The calculator presents your exact score, official WHO classification (underweight, normal weight, overweight, or obesity class), and computes your personalized healthy weight target range.

Step-by-Step Instructions

How to Calculate BMI

Choose your preferred unit system: Metric (cm and kg) or Imperial (feet, inches, and pounds).

Input your current standing height and body weight.

Click Calculate to see your BMI score, WHO category, and healthy target weight bracket.

Review the healthy weight range designed for your specific height.

Mathematical Precision

Standard BMI Formulas

Formula Definition

Metric Formula: BMI = Weight (kg) / [Height (m)]²
Imperial Formula: BMI = 703 × Weight (lbs) / [Height (inches)]²

Divide weight by the square of height. For imperial units (pounds and inches), multiply the ratio by conversion factor 703.

Variable Descriptions

Weight: Body weight in kilograms (kg) or pounds (lbs)
Height: Standing height in centimeters (cm) or feet & inches
703 Factor: Imperial conversion multiplier standard

Practical Walkthrough

Worked Example

Scenario: What is the BMI of an individual who is 175 cm (1.75 m) tall and weighs 70 kg?

Step 1: Square the height in meters: 1.75 × 1.75 = 3.0625 m².

Step 2: Divide weight by squared height: 70 ÷ 3.0625 = 22.86.

Step 3: Compare against WHO thresholds: 22.9 falls within 18.5 – 24.9 (Normal Weight).

Result:The individual has a BMI of 22.9, which is classified as Normal Weight.

Important Considerations & Tips

BMI is a population screening indicator and does not differentiate between lean muscle mass and fat tissue.
Athletes, bodybuilders, and pregnant women may register elevated BMI scores that do not reflect excess body fat.
This tool is intended for general educational awareness and should not replace professional clinical evaluation.

Search Questions Answered

Frequently Asked Questions

What is considered a healthy BMI range?

According to the World Health Organization (WHO), a BMI between 18.5 and 24.9 is considered the normal or healthy weight category for adults.

Why can BMI be misleading for muscular athletes?

BMI measures total weight relative to height and cannot differentiate muscle from adipose fat. Because muscle is denser than fat, muscular individuals often classify as overweight or obese despite having low body fat.

How do I calculate BMI using pounds and inches?

Multiply your weight in pounds by 703, then divide by your height in inches squared: BMI = (lbs × 703) / (inches × inches).

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