Calculator
BMI Calculator
Estimate your Body Mass Index (BMI) from height and weight and see where it falls on the standard reference scale.
BMI Calculator
Enter your height and weight to see your BMI.
This tool is for education and general interest only. It is not a medical device and must not be used to diagnose, treat or make health decisions. Always consult a qualified professional.
How to use it
- Step 1Choose metric or imperial units.
- Step 2Enter your height and weight.
- Step 3Read your BMI and its category on the scale.
What is BMI?
Body Mass Index (BMI) is a simple number that compares your weight to your height. It is calculated by dividing weight in kilograms by height in metres squared.
Doctors and researchers use BMI as a quick screening tool to place adults into broad categories: underweight, healthy weight, overweight and obese.
How to read your result
A BMI between 18.5 and 24.9 is generally described as the healthy-weight range for most adults. Below 18.5 is considered underweight, 25 to 29.9 overweight, and 30 or above the obese range.
BMI is only a starting point. It cannot tell the difference between muscle and fat, so very muscular people may score "overweight" while being extremely fit. It also does not consider age, sex or where fat is stored.
To understand the biology behind weight and energy, read our guides on metabolism and nutrition basics, or try the healthy weight calculator.
Questions & Answers
Frequently asked questions
No. BMI is a population-level screening tool, not a personal diagnosis. It can be misleading for athletes, older adults, pregnant people and children, who need different measures.
For most adults, a BMI of 18.5 to 24.9 is described as the healthy range. Your doctor can tell you what is appropriate for you.
No. BMI only uses height and weight. For a body-fat estimate, try our body fat estimator.
Understand the science
Go beyond the numbers
Every tool pairs with a guide that explains the biology behind it in plain language.