โ๏ธ BMI Calculator
Calculate your Body Mass Index and see where you fall on the BMI scale.
< 18.5 Normal
18.5โ24.9 Overweight
25โ29.9 Obese
30+
BMI Categories
How to Use the BMI Calculator
Our free BMI calculator makes it easy to determine your Body Mass Index in just a few simple steps. Whether you prefer Imperial or Metric measurements, we've got you covered.
Step 1: Select Your Unit System
Click the toggle at the top of the calculator to switch between Imperial (feet, inches, pounds) and Metric (centimeters, kilograms). The input fields will update automatically based on your selection.
Step 2: Enter Your Height
If using Imperial units, enter your height in feet and inches separately. For example, if you're 5 feet 10 inches tall, type "5" in the feet field and "10" in the inches field. If using Metric, simply enter your height in centimeters (e.g., 178).
Step 3: Enter Your Weight
Type your weight in pounds (Imperial) or kilograms (Metric). The calculator accepts decimal values for precision.
Step 4: View Your Results
Your BMI is calculated in real time as you type. The results include your BMI number, a color-coded category (Underweight, Normal, Overweight, or Obese), a visual gauge showing where you fall on the scale, and the healthy weight range for your height. Use these results as a general health indicator, but always consult a healthcare professional for personalized medical advice.
About Body Mass Index (BMI)
Body Mass Index (BMI) is a numerical value derived from a person's weight and height. It was developed by Belgian mathematician Adolphe Quetelet in the early 19th century and remains one of the most widely used screening tools for categorizing body weight.
How Is BMI Calculated?
BMI is calculated by dividing your weight in kilograms by the square of your height in meters: BMI = weight (kg) / height (m)ยฒ. For Imperial units, the formula is: BMI = (weight in lbs ร 703) / (height in inches)ยฒ.
Understanding BMI Categories
The World Health Organization (WHO) classifies BMI into four primary categories: Underweight (below 18.5), Normal weight (18.5โ24.9), Overweight (25โ29.9), and Obese (30 and above). These ranges help identify potential health risks associated with being underweight or overweight.
Limitations of BMI
While BMI is a useful screening tool, it has limitations. It doesn't distinguish between muscle and fat mass, meaning muscular individuals may have a high BMI despite being healthy. BMI also doesn't account for age, gender, ethnicity, or body composition. It should be used alongside other measurements like waist circumference, body fat percentage, and professional medical assessments for a comprehensive health evaluation.
Frequently Asked Questions
A healthy BMI falls between 18.5 and 24.9 according to the World Health Organization (WHO). This range is associated with the lowest risk of weight-related health problems. However, BMI is just one factor in overall health assessment.
BMI may overestimate body fat in athletes and people with significant muscle mass, since muscle weighs more than fat. A bodybuilder might have an "overweight" BMI while having very low body fat. For such individuals, body fat percentage or DEXA scans provide more accurate assessments.
Standard BMI categories are the same for adult men and women of all ages. However, for children and teens (ages 2โ20), BMI is calculated differently using age- and sex-specific percentile charts. Older adults may also carry different health implications at the same BMI as younger adults.
For most adults, checking BMI once every few months or during annual check-ups is sufficient. If you're actively working on weight management, monitoring monthly can help track progress. Remember that daily weight fluctuations are normal and don't significantly impact BMI.
A BMI above 25 is associated with increased risk of heart disease, type 2 diabetes, high blood pressure, sleep apnea, certain cancers, and joint problems. A BMI above 30 (obese) significantly increases these risks. Conversely, a BMI below 18.5 can indicate malnutrition, weakened immune function, and bone loss.