Body Mass Index (BMI) is a simple and widely used measurement that helps estimate whether your weight is healthy for your height.
This free BMI Calculator lets you calculate your BMI instantly using metric or imperial units, view your weight category, see your healthy weight range, and understand what your result means — all in a clean, mobile-friendly interface.
BMI Calculator
Calculate your Body Mass Index using metric or imperial units — with a clear category, healthy range, and BMI scale bar.
What Is BMI and Why It Matters
Body Mass Index (BMI) is a numerical value calculated from your height and weight to help categorize body weight into standard ranges such as underweight, normal weight, overweight, and obesity. It is commonly used by healthcare professionals as a screening tool to assess potential health risks related to body weight.
BMI does not directly measure body fat, muscle mass, or overall fitness. However, it provides a quick and practical estimate that can help identify whether someone may be at increased risk for conditions such as heart disease, diabetes, or high blood pressure when combined with other health indicators.
How BMI Is Calculated
- Metric formula:
Weight (kg) ÷ Height² (m²) - Imperial formula:
Weight (lb) ÷ Height² (in²) × 703
Our calculator automatically applies the correct formula based on the unit system you choose.
Understanding BMI Categories
BMI results are typically grouped into the following ranges:
- Underweight: Below 18.5
- Normal weight: 18.5 – 24.9
- Overweight: 25 – 29.9
- Obesity: 30 and above
These categories help provide context for your BMI score, but they are not a diagnosis. Factors such as age, sex, body composition, and lifestyle all play a role in overall health.
Healthy Weight Range
In addition to your BMI score, this calculator shows a healthy weight range based on your height. This helps you understand:
- What weight range aligns with a normal BMI
- How close your current weight is to that range
- How small changes in weight may affect your BMI
Frequently Asked Questions
1. What is a BMI calculator?
A BMI calculator measures your Body Mass Index using your height and weight to estimate whether your weight falls within a healthy range.
2. Is BMI accurate for everyone?
BMI is a general screening tool. It may not accurately reflect body composition for athletes, older adults, or people with higher muscle mass.
3. What is a healthy BMI range?
A healthy BMI for most adults is between 18.5 and 24.9.
4. Does age affect BMI results?
BMI calculations are the same for adults of all ages, but health interpretation may vary depending on age and lifestyle factors.
5. Does gender change BMI calculations?
The BMI formula is the same for males and females, but health considerations can differ — which is why this tool allows gender selection for clarity.
6. Can I use this BMI calculator on my phone?
Yes. The calculator is fully responsive and optimized for mobile, tablet, and desktop devices.
7. Is this BMI calculator free to use?
Yes. This tool is completely free with no signup, tracking, or data collection.
8. Does BMI measure body fat?
No. BMI estimates weight relative to height but does not directly measure body fat percentage.
