Understanding Your Body Mass Index (BMI)
The Body Mass Index (BMI) is a widely used screening tool that helps assess whether a person has a healthy body weight in proportion to their height. It's a simple calculation that provides a quick indicator of potential weight-related health risks for adults.
How is BMI Calculated?
The BMI calculation uses a straightforward formula:
- Metric System: BMI = weight (kg) / (height (m))^2
- Imperial System: BMI = (weight (lbs) / (height (inches))^2) * 703
Our calculator below allows you to easily compute your BMI using either metric or imperial units.
What Do Your BMI Results Mean?
BMI categories are standardized by the World Health Organization (WHO) for adults aged 20 and over:
- Underweight: Less than 18.5
- Normal weight: 18.5 – 24.9
- Overweight: 25.0 – 29.9
- Obesity: 30.0 or greater
It's important to remember that BMI is a screening tool, not a diagnostic one. It doesn't directly measure body fat or account for factors like muscle mass, bone density, overall body composition, or ethnic differences. For example, a very muscular athlete might have a high BMI but very little body fat, while an elderly person with low muscle mass might have a normal BMI but a higher percentage of body fat.
Limitations of BMI
While useful, BMI has limitations:
- It may overestimate body fat in athletes and people with a muscular build.
- It may underestimate body fat in older persons and others who have lost muscle mass.
- It does not differentiate between fat and muscle.
- It doesn't consider fat distribution (e.g., abdominal fat is riskier than fat on hips).
Always consult with a healthcare professional for a comprehensive assessment of your health and weight status.
How to Use the BMI Calculator
Using our BMI calculator is simple:
- Select your preferred unit system (Metric or Imperial).
- Enter your current weight in the designated field.
- Enter your current height in the designated field.
- Click the "Calculate BMI" button.
Your calculated BMI and its corresponding category will be displayed instantly.
Example Calculation:
Let's say a person weighs 70 kg and is 175 cm tall (Metric System):
- Height in meters = 175 cm / 100 = 1.75 m
- BMI = 70 / (1.75 * 1.75) = 70 / 3.0625 = 22.86
This BMI of 22.86 falls into the "Normal weight" category.
Another example: A person weighs 180 lbs and is 70 inches tall (Imperial System):
- BMI = (180 / (70 * 70)) * 703 = (180 / 4900) * 703 = 0.03673 * 703 = 25.82
This BMI of 25.82 falls into the "Overweight" category.