What is BMI?
BMI stands for Body Mass Index. It is a number calculated from weight and height and is commonly used as a screening measure for weight categories in adults.
Free Online Health Tool
BMI Calculator
Calculate your Body Mass Index using your height and weight. This free BMI calculator provides an instant adult BMI result and explains the standard BMI category associated with the result.
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Calculate Your BMI
Enter your height and weight below. The calculator is designed for adults.
What Is BMI?
BMI, or Body Mass Index, is a number calculated from a person's weight and height. It is commonly used as a screening measure to place adults into broad weight categories.
The BMI result can be useful as one part of a wider health assessment. It should be considered alongside factors such as age, waist circumference, physical activity, nutrition, medical history and other clinical information.
How Is BMI Calculated?
For metric measurements, BMI is calculated by dividing weight in kilograms by height in metres squared.
BMI = weight (kg) ÷ [height (m) × height (m)]
For imperial measurements, the standard formula uses weight in pounds, height in inches and a conversion factor.
BMI = [weight (lb) ÷ height (in)²] × 703
What Does My BMI Result Mean?
In adults, a BMI below 18.5 is commonly classified as underweight, 18.5 to less than 25 as healthy weight, 25 to less than 30 as overweight, and 30 or higher as obesity. These categories are general screening categories and should not be treated as a complete assessment of health.
BMI During Pregnancy
This calculator is intended for adult BMI screening and should not be used to assess pregnancy weight status. Pregnancy care uses individualized recommendations based on factors such as pre-pregnancy BMI, gestational age, fetal growth and clinical assessment.
BMI for Children and Teenagers
Adult BMI categories are not intended for children and adolescents. BMI interpretation in younger people uses age- and sex-specific growth references rather than the adult categories shown above.
Health information notice:
This calculator is provided for general educational and screening purposes.
It is not a substitute for medical diagnosis, individualized nutrition advice,
or consultation with a qualified healthcare professional.
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Frequently Asked Questions About BMI
What is a healthy BMI for adults?
A BMI from 18.5 to less than 25 is commonly classified as healthy weight in standard adult BMI categories. BMI alone does not determine whether a person is healthy.
Can I use this BMI calculator during pregnancy?
No. This calculator uses adult BMI categories and is not designed to assess pregnancy weight status. Pregnancy should be assessed using individualized clinical guidance.
Can children use this BMI calculator?
Adult BMI categories are not intended for children and adolescents. Their BMI is interpreted using age- and sex-specific growth references.
Does BMI measure body fat?
No. BMI does not directly measure body fat. Muscle mass, body composition, fat distribution and other individual factors can affect how BMI should be interpreted.
Should I speak with a healthcare professional about my BMI?
If you have concerns about your weight, nutrition, symptoms or overall health, discussing your individual situation with a qualified healthcare professional can provide more meaningful guidance than BMI alone.