BMI Calculator
Know Your Weight Category in Seconds
BMI Calculator
Calculate your Body Mass Index and get personalized insights
This tool provides a general estimate and is not a substitute for professional medical advice.
What is BMI Calculator?
Body Mass Index (BMI) is a numerical value calculated from a person’s weight and height. It was developed by Belgian mathematician Adolphe Quetelet in the 1800s and is now the most widely used screening tool for weight categories.
BMI is used by doctors and health organizations worldwide as a quick, cost-free way to identify potential weight problems in adults. While it does not directly measure body fat, it correlates well with direct fat measurements for most people.
Why does this matter?
Being in an unhealthy weight range — either underweight or obese — is linked to increased risk of diabetes, heart disease, high blood pressure, joint problems, and certain cancers. BMI is the first step in identifying that risk.
How to Use This Tool
- Enter your height in centimeters (e.g., 170 cm). If you know it in feet/inches, convert: 5'7" = 170 cm.
- Enter your current weight in kilograms (e.g., 75 kg). Use a reliable scale measured in the morning before eating.
- Click "Calculate BMI" to see your result instantly.
- Check your result against the BMI category table below to understand what it means.
Tips for Accurate Results
- BMI may overestimate body fat in athletes with high muscle mass.
- It may underestimate body fat in older people who have lost muscle (sarcopenia).
- Asian populations may face health risks at a lower BMI (above 23 is considered overweight in some guidelines).
- Measure your weight first thing in the morning for the most consistent results.
Frequently Asked Questions
Is BMI accurate for everyone?
BMI is a general screening tool. It is less accurate for athletes, the elderly, and pregnant women. It does not account for muscle mass, bone density, or fat distribution. Use it as a starting point, not a definitive diagnosis.
What BMI should I aim for?
For most adults, a BMI between 18.5 and 24.9 is considered healthy. However, optimal ranges may vary by ethnicity, age, and individual health factors. Your doctor can advise a personal target.
Can children use this calculator?
No. Adult BMI charts are not appropriate for children. Child BMI is calculated using age and gender-specific percentile charts from the WHO or CDC. Use our Child Growth Percentile Calculator instead.
How often should I check my BMI?
For most people, checking once every 3–6 months is sufficient. If you are actively managing your weight, monthly checks can help track progress. Avoid obsessing over daily fluctuations.
I have a normal BMI but feel unhealthy. Why?
BMI only considers weight and height. A “normal” BMI does not rule out other health issues like high blood pressure, poor nutrition, or metabolic disorders. Regular medical check-ups remain important.
- Medical Disclaimer: This tool is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before making health decisions.
How to Use This Tool
- Below 18.5 — Underweight
- 18.5 – 24.9 — Normal Weight
- 25.0 – 29.9 — Overweight
- 30.0 – 34.9 — Obese Class I
- 35.0 – 39.9 — Obese Class II
- 40.0 and above — Obese Class III
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