How to use the BMI calculator
Choose metric or US units, then enter your height and weight. The calculator shows your BMI, the category it falls into, and the weight range that would put you in the healthy band for your height.
BMI categories for adults
- Underweight: below 18.5
- Healthy weight: 18.5 to 24.9
- Overweight: 25 to 29.9
- Obesity: 30 and above
BMI formula
BMI is weight in kilograms divided by height in meters squared: BMI = kg ÷ m². In US units, use BMI = 703 × lb ÷ in².
Limitations of BMI
BMI does not distinguish muscle from fat, and it does not account for age, sex or where fat is carried. Athletes may score as overweight while being healthy. Use it as a screening tool alongside other measures such as waist size.
Frequently asked questions
What is a healthy BMI?
For most adults, a BMI from 18.5 to 24.9 is considered a healthy weight.
What is BMI Prime?
BMI Prime is your BMI divided by 25, the upper limit of the healthy range. A value above 1.0 means you are above that limit.