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About the BMI Calculator Tool
Check your Body Mass Index (BMI) to get a general idea of your weight status. Our simple calculator helps you understand where you fall on the BMI scale.
How to Calculate Your BMI
- Enter Your Weight: Input your current weight in kilograms (kg).
- Enter Your Height: Input your height in centimeters (cm).
Your BMI value and the corresponding weight category (e.g., Normal weight, Overweight) will be displayed instantly.
Disclaimer: BMI is a general indicator and does not account for factors like muscle mass. Consult a healthcare professional for personalized health advice.Related Tools:
📌 Frequently Asked Questions
What is a healthy BMI range?
According to the World Health Organization (WHO), a BMI between 18.5 and 24.9 is generally considered to be in the healthy weight range for most adults. A BMI below 18.5 is considered underweight, and a BMI of 25 or above is considered overweight.
Is my health data (height and weight) stored?
No. All calculations are performed on your device in your browser. The height and weight you enter are never sent to our servers, ensuring your health information remains completely private.
Is BMI accurate for everyone?
BMI is a useful population-level measure but may not be accurate for all individuals. It does not distinguish between fat and muscle mass. Therefore, very muscular individuals (like athletes) may have a high BMI but low body fat. It should be used as a general guide, not a definitive health assessment.
Free BMI Calculator: Calculate Your Body Mass Index
Introduction: Get a Quick Snapshot of Your Weight Status
Body Mass Index (BMI) is a widely used measure that provides a general indication of whether your weight is healthy in proportion to your height. The BMI Calculator from NexaPrep Tools is a free, simple, and private online tool that helps you calculate your BMI instantly. By entering your weight and height, you can get your BMI score and see which category you fall into, such as underweight, normal weight, or overweight. It's a useful starting point for understanding your health, and all calculations are performed privately in your browser, with no data ever being saved.
Why Calculate Your BMI?
While not a perfect diagnostic tool, BMI is a valuable and easy-to-calculate indicator for a variety of reasons.
- A Simple Health Indicator: BMI provides a quick and straightforward way to screen for potential weight-related health issues. A very high or very low BMI can be an indicator that further consultation with a healthcare professional is needed.
- Understand Weight Categories: The calculator instantly tells you where your BMI falls on the standard scale: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9), or Obesity (30 and above).
- Track Your Progress: If you are on a fitness or weight management journey, calculating your BMI periodically can be a simple way to track your progress over time.
- Population-Level Health Assessment: BMI is a critical tool for public health officials to study weight trends in a population and identify potential health risks on a large scale.
- Start a Conversation with Your Doctor: Your BMI score can be a useful starting point for a conversation with your doctor about your weight, diet, and overall health.
How to Calculate Your BMI: A Step-by-Step Guide
Our tool provides instant results as you enter your measurements:
- Enter Your Weight: Input your current weight in kilograms (kg).
- Enter Your Height: Input your height in centimeters (cm).
As soon as both values are entered, the output area will automatically update to show your calculated BMI score and the corresponding weight category, color-coded for easy interpretation.
The Formula Behind the BMI Calculation
BMI is calculated using a simple and standard formula:
BMI = Weight (kg) / [Height (m)]^2
Our calculator takes your height in centimeters, converts it to meters (by dividing by 100), squares it, and then divides your weight in kilograms by this result. This ensures the calculation is accurate and adheres to the standard definition of BMI.
Important Disclaimer: BMI is Not a Diagnostic Tool
It is essential to understand the limitations of BMI. BMI does **not** directly measure body fat and does not account for the difference between muscle and fat. This means:
- Very muscular individuals, like athletes, may have a high BMI and be classified as "overweight" even if they have very low body fat.
- Older adults, who tend to lose muscle mass, may have a "normal" BMI but a high percentage of body fat.
Your Health Data is Private
Your health information is highly personal. The NexaPrep Tools BMI Calculator is a 100% client-side tool. The weight and height you enter are processed by a script running in your browser on your own device. This data is never sent to our servers, logged, or stored. You can use our calculator with the complete confidence that your personal health data remains private.
BMI Calculator – Check Your Body Mass Index Free
What is BMI?
Body Mass Index (BMI) is a simple numerical measure calculated from your height and weight. It is widely used as a screening tool to categorize body weight into health categories. It was developed by Belgian mathematician Adolphe Quetelet.
BMI Formula
BMI = Weight (kg) / Height² (m²)
Or in imperial: BMI = 703 × Weight (lbs) / Height² (inches²)
BMI Categories (WHO Standard)
- 🔵 Underweight: BMI below 18.5
- 🟢 Normal weight: BMI 18.5 – 24.9
- 🟡 Overweight: BMI 25 – 29.9
- 🔴 Obese Class I: BMI 30 – 34.9
- 🔴 Obese Class II: BMI 35 – 39.9
- 🔴 Obese Class III: BMI ≥ 40
Important Limitations of BMI
- BMI does not measure body fat percentage directly.
- Athletes with high muscle mass can have a high BMI but low body fat.
- BMI does not account for age, gender, ethnicity, or fat distribution.
Use BMI as one of several health indicators — not the sole determinant. Always consult a doctor for complete health assessment.
BMI Calculator – Check Your Body Mass Index Free Online
What is BMI?
Body Mass Index (BMI) is calculated from your height and weight, and is widely used as a screening tool to categorize body weight into health ranges.
BMI Formula
BMI = Weight (kg) / Height² (m²)
BMI Categories (WHO Standard)
- 🔵 Underweight: BMI below 18.5
- 🟢 Normal weight: BMI 18.5 – 24.9
- 🟡 Overweight: BMI 25 – 29.9
- 🔴 Obese Class I: BMI 30 – 34.9
- 🔴 Obese Class II+: BMI ≥ 35
Important Limitations
- BMI does not measure body fat percentage directly.
- Athletes with high muscle mass can have a high BMI but low body fat.
- BMI doesn't account for age, gender, ethnicity, or fat distribution.
Use BMI as one of several health indicators — always consult a doctor for complete health assessment.
Free BMI Calculator – Body Mass Index Calculator | Metric & Imperial Units
Our free BMI calculator supports both metric (kg/cm) and imperial (lbs/inches) units, making it useful for users across the USA, UK, Canada, and Australia. Check your BMI against WHO standard categories and understand what your score means for your health.
BMI Standards by Country
- 🇺🇸 USA: Uses imperial units (lbs, inches) — our calculator supports both systems.
- 🇬🇧 UK: NHS recommends BMI checks for adults; normal range 18.5–24.9.
- 🇨🇦 Canada: Health Canada uses the same WHO BMI classifications.
- 🇦🇺 Australia: Used by Australian GPs as a standard screening metric.
- ⚠️ Important: BMI is a screening tool, not a diagnostic measure. Consult a doctor for health advice.