BMI Calculator
Check your body mass index, category, and healthy weight range instantly.
How to Use the BMI Calculator
Choose your preferred unit system, enter height and weight, and select Calculate BMI. The calculator converts imperial measurements into metric values so your results are accurate regardless of the numbers you provide.
After computing, the tool displays your BMI score, weight classification, and a quick summary of the range you fall into. Use the reset button to clear the fields and test different measurements for comparison.
BMI Formula and Categories
Body Mass Index is calculated as weight in kilograms divided by height in meters squared: BMI = kg ÷ m². The same formula applies worldwide and offers a fast way to screen for weight-related risks.
Category guidelines: Underweight (< 18.5), Normal weight (18.5 – 24.9), Overweight (25 – 29.9), and Obesity (30 and above). These ranges come from public health organizations and help identify when to speak with a medical professional.
Why BMI Matters and Its Limitations
BMI is widely used by doctors, insurers, and wellness programs because it correlates with health outcomes such as cardiovascular risk. It is also helpful for tracking progress when combined with other measurements like waist circumference or body fat percentage.
However, BMI does not measure body composition. Muscle, bone density, age, ethnicity, and pregnancy can affect interpretations. Use this calculator as a starting point and consult a healthcare provider for a full assessment.
Frequently Asked Questions
What formula does this BMI calculator use?
It applies the World Health Organization formula BMI = weight (kg) ÷ height (m)^2. When you use imperial units, the calculator converts them before computing your score.
What BMI range is considered healthy?
For most adults, a BMI between 18.5 and 24.9 falls within the healthy range. Values below 18.5 indicate underweight, and 25 or above signal overweight categories.
Is BMI an accurate measure for athletes?
BMI is a screening tool and does not distinguish between muscle and fat. Athletes with high muscle mass or older adults with low muscle mass may need additional assessments.