BMI Calculator
Calculate your Body Mass Index with metric or imperial units. See your BMI category and where you fall on the visual scale.
About BMI Calculator
Body Mass Index is one of the most widely used screening tools for assessing whether a person's weight is in a healthy range relative to their height. This calculator supports both metric and imperial inputs and includes a visual indicator so you can see exactly where your BMI falls on the standard scale.
Metric and Imperial Support
Toggle between centimeters and kilograms or feet/inches and pounds depending on what you are comfortable with. The calculator converts units internally and applies the correct BMI formula automatically.
BMI Categories
After entering your height and weight, you will see your numeric BMI value along with its corresponding category as defined by the World Health Organization:
- Underweight: BMI below 18.5
- Normal weight: BMI 18.5 to 24.9
- Overweight: BMI 25.0 to 29.9
- Obese: BMI 30.0 and above
Visual Scale
A color-coded visual indicator shows where your BMI sits on the spectrum, making it easy to understand your result at a glance. The scale spans from underweight through obese with clear color transitions.
Important Limitations
BMI is a population-level screening metric and does not measure body fat directly. It may overestimate body fat in muscular individuals and underestimate it in older adults who have lost muscle mass. For a complete health assessment, consult a healthcare professional who can consider factors like waist circumference, body composition, and medical history.
Your height and weight data are processed entirely in your browser and are never sent to any server.
Frequently Asked Questions
What is BMI and how is it calculated?
Body Mass Index (BMI) is a screening measure calculated by dividing weight in kilograms by height in meters squared (kg/m2). For imperial units, the formula is (weight in pounds x 703) / (height in inches)2. It provides a quick estimate of body fat based on height and weight.
What are the BMI categories?
The World Health Organization defines four main categories: Underweight is below 18.5, Normal weight is 18.5 to 24.9, Overweight is 25.0 to 29.9, and Obese is 30.0 and above. These ranges apply to adults aged 20 and older.
Is BMI an accurate measure of health?
BMI is a useful screening tool but has limitations. It does not distinguish between muscle and fat mass, so athletes may register as overweight despite being healthy. It also does not account for age, sex, bone density, or fat distribution. A healthcare provider can offer more comprehensive assessments.
Does this calculator work for children?
This calculator is designed for adults aged 20 and older. Children and teens require age-and-sex-specific BMI percentile charts because their body composition changes as they grow. Consult a pediatrician for child BMI assessments.