How to use BMI Calculator
- Choose centimeters and kilograms, or feet, inches, and pounds.
- Enter height and weight. BMI updates automatically.
- Read the category reference and the explanation before interpreting the number.
A closer look
Body mass index is weight in kilograms divided by height in meters squared. For example, 70 kg at 175 cm gives a BMI of about 22.86. This page uses the CDC adult reference for people aged 20 and older: below 18.5, 18.5 to below 25, 25 to below 30, and 30 or above. BMI is a general screening calculation, not a medical diagnosis. It does not directly measure body fat or distinguish muscle from fat, and it cannot describe someone’s health on its own.
A practical example
Enter 70 kg and 175 cm to calculate a BMI of about 22.86. The number is a general adult screening measure; it does not assess health on its own.
A useful tip
Children and teenagers need age- and sex-specific BMI interpretation. Pregnancy and individual circumstances can also make a simple adult category unsuitable.
Good questions. Simple answers.
Why can the category differ from the rounded number?
The category uses the full calculated value. The displayed BMI is rounded to two decimal places, so a value very close to a boundary can look like the boundary.
Does this provide a diagnosis?
No. It shows a mathematical screening value and a general adult reference. A qualified healthcare professional can interpret measurements in context.
Explore all calculators for related tasks and category-specific guidance, or read how Toolzafi handles your data.