BMI Calculator
Calculate your Body Mass Index.
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Comprehensive Calculation Guide & Methodology
How the BMI Calculator Works
Overview & Practical Utility
Body Mass Index (BMI) is a standardized screening metric used globally by health organizations to categorize body weight relative to stature. While BMI does not differentiate between lean muscle mass and adipose tissue, it provides a fast, validated initial baseline for assessing health risks associated with underweight, overweight, and obesity.
Body Mass Index (Metric & Imperial Equations)
Mathematical equation and computational variables used in this tool
\text{BMI (Imperial)} = 703 \times \frac{\text{Weight (lbs)}}{\text{Height (inches)}^2} \quad | \quad \text{BMI (Metric)} = \frac{\text{Weight (kg)}}{\text{Height (m)}^2}
In imperial units, weight in pounds is divided by height in inches squared, then multiplied by the 703 conversion constant. Standard WHO classifications: Underweight (< 18.5), Normal Weight (18.5–24.9), Overweight (25.0–29.9), and Obesity (30.0+).
Worked Step-by-Step Example
Calculating BMI for an individual who is 5 feet 10 inches tall (70 inches) and weighs 175 pounds.
Height5 ft 10 in (70 inches / 1.778 m)
Weight175 lbs (79.38 kg)
Calculation Steps:
- 1Convert height to inches: (5 × 12) + 10 = 70 inches.
- 2Square the height: 70 × 70 = 4,900.
- 3Divide weight by height squared: 175 ÷ 4,900 ≈ 0.035714.
- 4Multiply by 703 conversion factor: 0.035714 × 703 ≈ 25.1.
Result: BMI of 25.1 (Classified as borderline Overweight / Upper Normal range).
Pro Tips & Best Practices
- Athletes and weightlifters with high muscle density may score high BMI values despite having low body fat percentages. Pair BMI with waist-to-hip ratio or skinfold measurements.
- Consult with a physician or registered dietitian for comprehensive clinical health evaluations.
Frequently Asked Questions (FAQ)
Common questions about the BMI Calculator and underlying formulas
Related Guides & Articles
Learn how to calculate your body fat percentage accurately with tape measurements using the U.S. Navy method and our step-by-step worked example.
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