Free Body Mass Index Calculator - Calculate Your BMI Online
Calculate your BMI (Body Mass Index) instantly with our free, accurate calculator. Support for kilograms, pounds, centimeters, inches, and more. Get your BMI results based on WHO international standards and understand your healthy weight range.
Free BMI Calculator - Calculate Your Body Mass Index
Your BMI Results - Body Mass Index Calculation
Height
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Weight
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BMI Value
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Status
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<18.5Underweight
18.5-24.9Normal
25-29.9Overweight
≥30Obese
What is Body Mass Index?
Body Mass Index (BMI) is a numerical measure of body fat based on an individual's weight and height. It applies to adult men and women and serves as a screening tool to identify potential weight-related health problems.
BMI Calculation Method
The BMI calculation uses a mathematical formula that divides your weight in kilograms by the square of your height in meters.
BMI = weight (kg) / [height (m)]²
Example: For a person weighing 70 kg with height 1.75 m: BMI = 70 ÷ (1.75 × 1.75) = 22.86
This BMI calculator supports multiple units including kilograms (kg), pounds (lbs), stones (st) for weight, and centimeters (cm), meters (m), inches (in), feet (ft) for height, making it easy to calculate your body mass index regardless of your preferred measurement system.
BMI Chart - Understanding BMI Categories and Ranges
Classification
BMI Range
Health Risk
Underweight
< 18.5
Possible nutritional deficiency
Normal Weight
18.5 - 24.9
Low risk - Optimal range
Overweight
25.0 - 29.9
Moderate risk
Obese Class I
30.0 - 34.9
High risk
Obese Class II
35.0 - 39.9
Very high risk
Obese Class III
≥ 40.0
Extremely high risk
History of BMI - Who Invented the Body Mass Index?
Adolphe Quetelet (1796-1874), a Belgian mathematician and statistician, developed the foundational formula between 1830 and 1850. Originally termed the "Quetelet Index," it emerged from his work in social physics.
The modern term "Body Mass Index" was introduced in 1972 by American physiologist Ancel Keys. His research established BMI as the preferred metric, leading to widespread adoption by the WHO (World Health Organization) and CDC (Centers for Disease Control and Prevention).
WHO BMI Standards - World Health Organization BMI Classification
The World Health Organization (WHO) has established international BMI classification standards that are widely used globally. The WHO recognizes that BMI is a simple index of weight-for-height commonly used to classify underweight, overweight and obesity in adults.
The WHO standard BMI classification applies to both men and women aged 18 years and above. These standards were developed based on extensive research and epidemiological studies across diverse populations.
WHO Classification
BMI (kg/m²)
Risk of Co-morbidities
Underweight (Severe thinness)
< 16.0
High
Underweight (Moderate thinness)
16.0 - 16.9
Moderate
Underweight (Mild thinness)
17.0 - 18.4
Low
Normal range
18.5 - 24.9
Average
Overweight (Pre-obese)
25.0 - 29.9
Increased
Obese Class I
30.0 - 34.9
Moderate
Obese Class II
35.0 - 39.9
Severe
Obese Class III
≥ 40.0
Very severe
WHO Standards for Asian Populations:
The WHO has also recognized that Asian populations have different associations between BMI, percentage of body fat, and health risks. For Asian populations, the WHO recommends additional trigger points for public health action:
Classification
BMI (kg/m²)
Risk Level
Underweight
< 18.5
Low (but risk of other clinical problems)
Normal range
18.5 - 22.9
Average
Overweight
23.0 - 24.9
Increased
Obese I
25.0 - 29.9
Moderate
Obese II
≥ 30.0
Severe
These Asian-specific cutoff points reflect the higher risk of type 2 diabetes and cardiovascular disease at lower BMI levels in Asian populations compared to European populations.
BMI Limitations - Important Considerations for BMI Calculator Results
Muscle Mass: BMI doesn't differentiate between muscle and fat. Athletes and bodybuilders may have high BMI despite low body fat.
Age Factors: Older adults naturally lose muscle mass. A higher BMI may be healthier for seniors.
Ethnic Differences: Different populations have varying body compositions at the same BMI.
Fat Distribution: BMI doesn't indicate where fat is stored. Abdominal fat poses greater health risks.
BMI should be used alongside other health assessments including waist circumference, body fat percentage, and comprehensive medical evaluation for accurate health status determination.
Embed BMI Calculator
Add our free BMI calculator to your website or application
Embed BMI Calculator on Your Website
You can easily embed our BMI calculator on your website using an iframe. Simply copy the code below and paste it into your HTML:
Free, accurate, and easy-to-use Body Mass Index calculator
Our Mission
We created this free BMI calculator to help people around the world easily calculate and understand their Body Mass Index. Our goal is to provide a simple, accurate, and accessible tool that promotes health awareness and helps individuals make informed decisions about their wellness.
Why We Built This Tool
Body Mass Index is an important health metric, but many BMI calculators online are cluttered with ads, require registration, or provide inaccurate information. We wanted to create a completely free tool that:
Provides instant, accurate BMI calculations
Supports multiple measurement units worldwide
Is based on WHO international standards
Requires no registration or personal data
Works on all devices - desktop, tablet, and mobile
Can be embedded on other websites for free
Free and Open
This BMI calculator is completely free to use. We believe health tools should be accessible to everyone, which is why we don't require registration, don't collect personal information, and allow anyone to embed this calculator on their website.
Whether you're an individual tracking your health, a fitness professional, a healthcare provider, or a website owner looking to add a BMI calculator to your site, our tool is free for you to use.
Accuracy and Standards
Our calculator uses the standard BMI formula endorsed by the World Health Organization (WHO) and Centers for Disease Control and Prevention (CDC). We've implemented both international standards and Asian-specific BMI categories to provide the most relevant health information for users worldwide.
Privacy
We respect your privacy. This calculator performs all calculations in your browser - we don't store, transmit, or collect any of your health data. Your height, weight, and BMI results remain completely private to you.
Contact Us
Get in touch with the BMI Calculator team
We'd Love to Hear From You
Thank you for using our free BMI calculator! While we don't have a traditional contact form or email support (to keep this tool completely free), there are several ways you can connect with us or get help.
Frequently Asked Questions
Most questions can be answered by reading our comprehensive information sections on the home page, which cover:
What BMI is and how it's calculated
BMI categories and health risks
WHO international standards
BMI limitations and considerations
History and development of BMI
Report Issues
If you encounter any technical issues, bugs, or calculation errors, please note the following details and report them through our feedback system:
What device and browser you're using
The height and weight values you entered
What units you selected
What you expected to happen vs. what actually happened
Embed Support
If you need help embedding this calculator on your website, please visit our Embed page for detailed instructions and code examples. The embed code is ready to copy and paste.
Medical Advice
Important: We cannot provide personal medical advice. This BMI calculator is an educational tool only. If you have specific health concerns or questions about your BMI results, please consult with a qualified healthcare provider, doctor, or registered dietitian.
Suggestions and Feedback
We're always looking to improve this tool! If you have suggestions for new features, additional information to include, or ways to make the calculator more useful, we'd love to hear your ideas.
Your feedback helps us make this free tool better for everyone.
Partnerships and Collaborations
If you're interested in partnering with us or have collaboration opportunities, we're open to discussions that help us maintain this free tool and expand health education resources.