BMI Calculator
Free BMI Calculator
BMI Calculator
What is BMI?
Body Mass Index (BMI) is a simple measurement that helps you understand if your weight is in a healthy range for your height. While it’s not perfect, it’s a quick and useful screening tool used by doctors and health professionals worldwide.
Find Your Body Mass Index (BMI)
How to Use This Calculator
- Select your gender
- Choose between Metric (cm/kg) or Imperial (feet/inches/pounds)
- Enter your height and weight
- Click “Calculate My BMI”
BMI Categories
| BMI Range | Category | What It Means |
|---|---|---|
| Below 18.5 | Underweight | You may need to gain some weight |
| 18.5 – 24.9 | Normal | This is considered a healthy range |
| 25.0 – 29.9 | Overweight | You may be at higher risk for health issues |
| 30.0 and above | Obese | Higher risk of serious health problems |
Note: The BMI categories above are the same for both men and women. However, women naturally carry more body fat than men at the same BMI, while men usually have more muscle mass.
BMI Chart
Understanding Your BMI Result
Your Body Mass Index (BMI) is a quick way to assess whether your current weight falls within a healthy range for your height. While BMI isn’t perfect, it doesn’t account for muscle mass, age, or body composition. BMI still widely used by healthcare professionals as a reliable screening tool.
Why BMI Matters
Maintaining a healthy BMI can significantly reduce your risk of serious conditions like heart disease, type 2 diabetes, and high blood pressure. Whether you’re trying to lose weight, gain muscle, or simply stay healthy, knowing your BMI is a great first step toward better health decisions.
Ready to check your BMI? Use the calculator above to get your result instantly. It works for both Metric and Imperial measurements.
How to Calculate BMI: Metric and Imperial Formulas
Understanding the BMI formula allows you to manually track your health metrics without needing a digital tool. Body Mass Index (BMI) is a calculation that uses your height and weight to estimate body fat and screen for weight categories that may lead to health problems.
The Metric BMI Formula
The standard international method for calculating BMI uses the metric system (kilograms and meters).
Formula: Weight (kg) / [Height (m)]²
Metric Example:
-
Weight: 70 kg
-
Height: 1.75 m
-
Calculation: 70 / (1.75 x 1.75) = 22.86
The Imperial BMI Formula (Pounds and Inches)
If you are using the US Imperial system, you must include a conversion factor of 703 to get an accurate result.
Formula: (Weight (lbs) x 703) / [Height (in)]²
Step-by-Step Imperial Example: To calculate the BMI for a person who weighs 120 lbs and is 5’3″ (63 inches) tall:
-
Step 1: Multiply weight by 703:
120 x 703 = 84,360 -
Step 2: Square the height in inches:
63 x 63 = 3,969 -
Step 3: Divide the first number by the second:
84,360 / 3,969 = 21.25
The Result: A BMI of 21.3 is considered a Healthy Weight based on standard health charts.
Why Use a BMI Calculator?
While the manual BMI calculation is a great way to understand the math, using a precise BMI calculator ensures there are no rounding errors. Tracking your BMI is a helpful starting point for discussing body composition and overall wellness with a healthcare provider.
Note: BMI is a screening tool and does not directly measure body fat or muscle mass.
BMI for Children and Teens: How It Works
While the BMI formula for children and teens is the same as the one used for adults, the way the results are interpreted is very different.
In adults, BMI is a fixed category. However, in growing children, the amount of body fat changes constantly with age. Furthermore, body fat
composition varies significantly between boys and girls as they develop. Because of these factors, a single BMI number isn’t enough to
determine a child’s health status.
Understanding BMI Percentiles
To provide an accurate assessment, health professionals use BMI-for-age percentiles. After calculating a child’s BMI, the result is plotted on a
CDC growth chart that accounts for the child’s specific age and sex.
These percentiles compare a child’s BMI to that of thousands of other children in the same demographic.
A simple method to find your child’s BMI percentile is by using the CDC’s online Child and Teen BMI Calculator – BMI percentile calculator.
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