BMI Calculator
Free online BMI calculator. Check your Body Mass Index (BMI) to see if you are underweight, normal weight, overweight, or obese.
Your BMI
22.9
Within the healthy weight range for your height.
Healthy range
—
For your height
To reach normal
—
—
Method
How this calculator works
BMI compares weight to height squared. The squared height accounts for the fact that taller people have more total mass even at the same body composition.
Metric: BMI = weight(kg) / height(m)²
Imperial: BMI = (weight(lb) / height(in)²) × 703- Choose your unit system — metric (kg, cm) or imperial (lb, in).
- Enter your current weight and height.
- The calculator squares your height and divides weight by it (multiplied by 703 for imperial).
- Your BMI value is matched against WHO categories: <18.5 underweight, 18.5–24.9 normal, 25–29.9 overweight, ≥30 obese.
- The healthy weight range (BMI 18.5–24.9) for your height is computed in reverse so you know the target.
Examples
Worked examples
Real numbers, end-to-end results.
70 kg · 175 cm
BMI 22.9 · Normal
Healthy range: 56.7 – 76.3 kg.
154 lb · 69 in
BMI 22.7 · Normal
Same person, imperial units — the result is essentially identical.
90 kg · 170 cm
BMI 31.1 · Obese
About 17 kg above the upper end of the healthy range.
Use cases
When to use it
- Quick screening of weight status during routine self-check-ins.
- Identifying a healthy weight target for your height.
- Tracking weight changes against a clear numerical reference.
- Comparing body composition trends over time alongside other markers.
Disclaimer: This calculator provides estimates for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for decisions affecting your health.
Sources: Formulas sourced from WHO BMI classifications, Mifflin-St Jeor equation (1990), Harris-Benedict equation, and NIH/CDC published guidelines. Not intended for clinical diagnosis.
FAQ
Frequently asked questions
What is a healthy BMI?
Is BMI an accurate measure of health?
How is BMI calculated?
Do men and women have different BMI charts?
Why is my BMI high if I am very muscular?
Methodology, assumptions & limitations
How we calculate: This calculator uses standard, peer-reviewed mathematical formulas implemented in TypeScript. All calculations run entirely in your browser — no data is sent to any server.
Assumptions: Unless stated otherwise, calculations assume constant rates over the specified period, no taxes or fees beyond those explicitly input, and standard compounding conventions for the formula type.
Limitations: Results are estimates for planning purposes. Real-world outcomes may differ due to variable rates, regulatory changes, taxes, fees, inflation, or other factors not modeled. This tool does not constitute medical advice or clinical diagnosis.
When NOT to use this: Do not rely solely on this calculator for medical decisions or diagnoses — always consult a qualified healthcare provider.
Feedback: Found an error or have a suggestion? Contact us — we review and correct reported issues within 48 hours.
Deep Dive Guide
Bmi Guide
Comprehensive guide for bmi.
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