ABOUT
About Winz Calculator
Winz Calculator is a free, privacy-first BMI calculator built on WHO and CDC guidelines, designed to give you instant, educational health context.
What Winz Calculator Does
Winz Calculator is a free, easy-to-use online Body Mass Index (BMI) calculator. It helps you quickly assess your weight status using standard adult guidelines and provides instant result guidance, a healthy weight range, and educational context about BMI interpretation.
Our calculator supports both metric (kilograms and centimetres) and imperial (pounds, feet and inches) measurements. All calculations run entirely in your browser — no personal data is ever sent to our servers.
How BMI Is Calculated
Our calculator uses the standard BMI formulas endorsed by the World Health Organization (WHO) for adults.
Metric Formula
BMI = weight (kg) ÷ height (m)²Imperial Formula
BMI = 703 × weight (lb) ÷ height (in)²Both formulas produce equivalent results. The metric formula is the international standard; the imperial formula applies a constant (703) to convert to consistent units.
Adult BMI Categories (WHO)
| Category | BMI Range |
|---|---|
| Severe Thinness | < 16.0 |
| Moderate Thinness | 16.0 – 16.9 |
| Mild Thinness | 17.0 – 18.4 |
| Normal weight | 18.5 – 24.9 |
| Overweight | 25.0 – 29.9 |
| Obese Class I | 30.0 – 34.9 |
| Obese Class II | 35.0 – 39.9 |
| Obese Class III | ≥ 40.0 |
BMI for Children and Teens (Ages 2–20)
For children and adolescents aged 2–20, BMI interpretation is more complex. The Centers for Disease Control and Prevention (CDC) recommends using age- and sex-specific growth charts to determine a BMI percentile ranking.
Limitations of BMI
BMI is a practical population-level screening tool, but it does not directly measure body fat and may not fully reflect individual health status for people with high muscle mass, different ethnic backgrounds, older adults, or during pregnancy.
For a comprehensive health assessment, healthcare providers typically consider BMI alongside other measures such as waist circumference, blood pressure, blood glucose, and cholesterol.
Medical Disclaimer
Winz Calculator is not a substitute for professional medical advice. BMI is a screening tool, not a diagnostic tool. It does not directly measure body fat or account for individual health factors. Always consult a qualified healthcare provider for personalised health advice, diagnosis or treatment.