How the BMI Calculator Works
The DwellixTools BMI Calculator measures your Body Mass Index (BMI) — a widely recognized medical metric established by the World Health Organization (WHO) to classify an adult’s weight relative to their height.
Our calculator supports both measurement systems:
- Metric System: Weight in kilograms (kg) and height in centimeters (cm).
- US Customary System: Weight in pounds (lbs) and height in feet and inches (ft/in).
World Health Organization (WHO) BMI Categories
The WHO classifies BMI scores into four main categories for adult men and women:
| BMI Range | Category | Health Risk Status |
|---|---|---|
| Below 18.5 | Underweight | Increased risk of nutritional deficiency |
| 18.5 – 24.9 | Normal Weight | Optimal health range |
| 25.0 – 29.9 | Overweight | Mild to moderate risk |
| 30.0 and above | Obese | High health risk |
Mathematical Formulas for BMI
Our calculator computes your score using official medical formulas:
Metric Formula
BMI = weight (kg) / (height (m))²
Example: A person weighing 70 kg and standing 175 cm (1.75 m) tall: 70 / (1.75 × 1.75) = 22.86
US / Imperial Formula
BMI = (weight (lbs) / (height (inches))²) × 703
Example: A person weighing 160 lbs and standing 5 ft 10 in (70 inches) tall: (160 / (70 × 70)) × 703 = 22.95
Limitations of Body Mass Index (BMI)
While BMI is an excellent screening tool for general populations, it has known limitations:
- Athletes & Bodybuilders: BMI does not distinguish between muscle mass and fat mass. Muscular individuals may be classified as “overweight” despite low body fat.
- Elderly Adults: Older adults naturally lose muscle density, which may cause BMI to underestimate body fatness.
- Pregnant Women: BMI formulas do not apply to pregnant or lactating individuals.
Frequently Asked Questions (FAQ)
What is a healthy BMI range?
A healthy BMI for adults is generally considered between 18.5 and 24.9.
Is my personal health data saved anywhere?
No. All calculations are performed 100% locally in your web browser. Your height, weight, and age are never saved or sent to any server.