What adult BMI measures
Body Mass Index compares weight with height. It is a screening measure used for adults and does not directly measure body fat, muscle, bone, fluid or overall health.
How to calculate BMI
In metric units, BMI equals weight in kilograms divided by height in metres squared: BMI = kg ÷ m². A person weighing 70 kg at 1.75 m has a BMI of about 22.9.
Imperial measurements can be converted to kilograms and metres before the same formula is used. ToolBullet performs those conversions using 1 pound = 0.45359237 kilograms and 1 inch = 0.0254 metres.
Standard adult screening categories
Common adult categories are below 18.5, 18.5–24.9, 25.0–29.9 and 30 or above. These are population screening references rather than diagnoses or personalised weight targets.
Important limitations
- BMI does not distinguish fat from muscle or show fat distribution.
- Adult categories are not used in the same way for children or during pregnancy.
- Age, ethnicity, muscularity, health history and other clinical information can affect interpretation.
- A single BMI result cannot diagnose a condition or determine an individual treatment plan.
Using the result
Treat BMI as one screening data point. A qualified healthcare professional can interpret it alongside symptoms, waist measurement, blood pressure, laboratory results, medical history and other relevant information.