BMI Calculator
Calculate your Body Mass Index using the World Health Organization formula. Free, instant, no sign-up required.
About BMI
What is BMI?
Body Mass Index (BMI) is a number calculated from your height and weight. It is widely used as a screening tool to identify possible weight problems in adults. BMI is a reliable indicator of body fat for most people.
What formula is used?
We use the standard WHO formula: BMI = Weight (kg) ÷ Height (m)². For imperial units, we convert your measurements before applying the formula.
What are the BMI categories?
Underweight: below 18.5 | Normal weight: 18.5–24.9 | Overweight: 25–29.9 | Obese: 30 and above. These are defined by the World Health Organization.
Is BMI accurate?
BMI is a useful screening tool but has limitations. It does not directly measure body fat and may overestimate body fat in athletes and underestimate it in older persons. Use our Body Fat Calculator for a more accurate body composition estimate.