About BMI
Body Mass Index (BMI) is a measure of body fat based on height and weight. It's calculated by dividing weight in kilograms by height in meters squared.
BMI Categories
- Underweight: BMI less than 18.5
- Normal weight: BMI 18.5–24.9
- Overweight: BMI 25–29.9
- Obese: BMI 30 or greater
⚠️ Note: BMI is a screening tool, not a diagnostic. Consult a healthcare professional for medical advice.
Usage Guide
BMI is simple to use. Enter your values in the input fields — the tool processes them in real time. Choose between different calculation modes or conversion directions if available. Results update automatically as you type. Use the copy or download button to save your results for reference or sharing.
Best Practices
- Double-check your input values before relying on the results
- Use the swap or reverse functionality to convert in both directions
- Bookmark the tool for quick access when you need it regularly
- Share results by using the copy-to-clipboard feature
- Enter precise values for the most accurate calculations
Frequently Asked Questions
Is this tool really free?
Yes, BMI is 100% free to use with no registration, no hidden fees, and no usage limits. There is no premium version or paid tier — every feature is available to everyone.
What are the limitations?
Results are for informational purposes. For critical financial, legal, or medical decisions, consult a qualified professional.
Does it work offline?
Most tools run entirely in your browser using client-side JavaScript. Once the page is fully loaded, many features work without an active internet connection. However, the initial page load requires internet access.
Is my data private?
Your data never leaves your browser. All processing happens client-side — nothing is uploaded to any server. You can verify this by checking the browser Developer Tools network tab while using the tool.