balance_scale BMI Calculator
Calculate your Body Mass Index (BMI) and understand what it means for your health. Get your BMI category and healthy weight range recommendations.
Enter values and click Calculate.
PDF Document Viewer
Upload a PDF to view alongside your calculations.
Notes
Record your calculation notes here. Saved locally on your device.
Frequently Asked Questions - BMI Calculator
What is BMI and how is it calculated?
BMI (Body Mass Index) is a screening measure calculated as weight (kg) divided by height squared (m2). It provides a rough estimate of body fat, but does not measure body fat directly. It is used as a population-level tool to identify potential weight-related health risks.
What are the BMI categories?
The WHO categories are: Underweight (below 18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obese Class I (30-34.9), Obese Class II (35-39.9), and Obese Class III (40+). These categories are associated with increasing health risks.
What are the limitations of BMI?
BMI does not distinguish between muscle and fat. Athletes with high muscle mass may be classified as overweight or obese. It does not account for body fat distribution, age, sex, or ethnicity. Waist circumference and body fat percentage provide additional insight.
Is BMI interpreted differently for different ethnicities?
Yes. For Asian populations, lower BMI cutoffs are recommended (overweight at 23+, obese at 27+) due to higher body fat percentages at the same BMI. Different ethnic groups have varying relationships between BMI and health risks.
What is a healthy BMI for children and teens?
BMI for children is interpreted using age and sex-specific percentile charts rather than fixed categories. A child's BMI between the 5th and 85th percentile is considered healthy. The calculation is the same, but interpretation differs from adults.
All Calculators
Explore our full suite of free online calculators.