BMI Calculator
Calculate body mass index from height and weight in kilograms and centimeters or pounds, feet and inches. View the result and general adult category.
Calculator arithmetic runs locally in your browser and does not require an API.
The interactive calculator loads here when JavaScript is enabled.
How to use BMI Calculator
Choose units before entering measurements. Switching units does not convert existing numbers; re-enter them. Adult category interpretation is intended for ages 20 and over, not children or pregnancy.
Formula and method
BMI = weight in kilograms / height in meters squared. Imperial inputs are converted using 1 lb = 0.45359237 kg and 1 in = 2.54 cm before the same formula is applied.
Understanding the results
The categories are below 18.5, 18.5 to below 25, 25 to below 30, and 30 or above. Classification uses unrounded BMI. BMI is a screening measure, not a direct body-fat measurement or diagnosis.
Worked example
For an adult weighing 70 kg at 175 cm, BMI = 70 / 1.75² = 22.86 when rounded. The unrounded value falls in the general healthy / normal range.
Results are estimates for general information, not a diagnosis or a substitute for professional medical advice.
References
Frequently asked questions
Does BMI measure body-fat percentage?
No. It uses weight relative to height without separating fat, muscle or other tissue.
Can I use the adult categories for a child?
No. Children and teens need age-specific interpretation; this tool does not provide BMI-for-age percentiles.
Why might the rounded value appear on a boundary?
The category uses the unrounded calculation, while the displayed number is rounded to two decimal places.