How to Use Our BMI Calculator
Provide the following information for an accurate BMI calculation. This calculator works for adults aged 20 and over.
-
Gender: Select Male or Female. While the core BMI formula is the same for all adults, your gender can influence body composition, and this information helps provide more personalized context.
-
Age: Enter your current age. BMI is interpreted differently for children and teens, so it’s important to use an adult calculator if you are 20 or older.
-
Weight: Enter your current weight. You can use pounds (lbs) or kilograms (kg).
-
Height: Enter your height in feet and inches (ft/in) or in centimeters (cm).
Understanding Your Results
Your result is your BMI score, a single number that classifies your weight into one of four main categories. BMI is a screening tool used to identify potential weight-related health risks; it is not a diagnostic tool and does not measure body fat directly.
The standard weight status categories, as defined by the World Health Organization (WHO), are:
Adult BMI Categories
For a more detailed breakdown, the Obesity category is often subdivided:
-
30.0 – 34.9: Obesity Class I
-
35.0 – 39.9: Obesity Class II
-
40.0 and Above: Obesity Class III (Severe Obesity)
A higher BMI is associated with an increased risk for certain conditions like heart disease, high blood pressure, and type 2 diabetes. However, it’s crucial to consider BMI as part of a larger picture that includes your lifestyle, diet, and other health markers.
Frequently Asked Questions
Is BMI an accurate measure of health?
BMI is a good starting point but it is not a perfect measure of health. It’s a simple, inexpensive screening tool that assesses your weight relative to your height. It provides a general idea of whether your weight might pose a health risk. However, it doesn’t tell the whole story. A truly accurate assessment of health involves looking at blood pressure, cholesterol levels, blood sugar, diet, physical activity, and family history.
What are the limitations of the BMI calculator?
The primary limitation of BMI is that it cannot distinguish between fat and muscle mass. Muscle is much denser than fat, so individuals who are very muscular (like athletes or bodybuilders) can have a high BMI that classifies them as “Overweight” or “Obese” even though their body fat is very low.
Other limitations include:
-
It doesn’t account for body fat distribution: Fat stored around the abdomen (visceral fat) is more dangerous than fat stored in the hips and thighs. BMI doesn’t differentiate this.
-
It may not be accurate for all ethnic groups: Body composition can vary between ethnic groups. For example, some studies suggest that people of Asian descent may have a higher health risk at a lower BMI compared to people of European descent.
-
It doesn’t consider age-related changes: Older adults naturally lose muscle mass, so their BMI might appear “normal” even if their body fat percentage is high.
I’m an athlete with a lot of muscle. Is my “Overweight” BMI result wrong?
This is a classic example of BMI’s limitations. If you are an athlete or have a high degree of muscle mass, your BMI result is likely not a good indicator of your health or body fat percentage. Your weight is higher due to dense muscle, not excess fat. In your case, other methods like skinfold caliper measurements, bioelectrical impedance analysis (BIA), or a DEXA scan would provide a much more accurate assessment of your body composition.
If my BMI is high, what are the next steps I should take?
If your BMI falls into the overweight or obese categories, the most important next step is to talk to your doctor or a registered dietitian. Do not panic or start an extreme diet. A healthcare professional can perform a full health assessment, including checking your blood pressure and cholesterol, and discuss your lifestyle. They can help you create a safe and sustainable plan that focuses on balanced nutrition and regular physical activity, rather than just the number on the scale.
Concrete Example: If a 5’9″ (175 cm) person weighs 200 lbs (90.7 kg), their BMI is 29.5, which is in the “Overweight” category. Their doctor might suggest a modest weight loss goal of 5-10% of their body weight (10-20 lbs) to significantly reduce health risks, achieved through small, consistent changes like walking 30 minutes a day and adding more vegetables to their meals.
Is the BMI calculation different for children and teens?
Yes, absolutely. For individuals under 20, BMI is calculated using the same formula but is interpreted differently. Instead of fixed categories, a child’s or teen’s BMI is plotted on age- and sex-specific percentile charts. This is because their body composition changes significantly as they grow. A result in the 85th percentile, for example, means the child’s BMI is higher than 85% of other children of the same age and sex. This calculator should only be used for adults.
Understand Your Body Better
Now that you know your BMI, you can explore other key health metrics. Calculate your body’s baseline energy needs with our Basal Metabolic Rate (BMR) Calculator. To get a complete picture of your daily calorie needs based on your activity level, use our TDEE (Total Daily Energy Expenditure) Calculator.
