BMI Calculator
Free BMI Calculator
This BMI calculator estimates your body mass index using your height and weight. BMI is a quick screening number that compares body weight to height. It does not diagnose health, but it can help you understand whether your weight falls into a general range commonly used for adults.
BMI is useful because it is simple, fast, and easy to compare over time. However, it has limits. It does not directly measure body fat, muscle, bone density, waist size, pregnancy status, or athletic build. A muscular person may have a high BMI without having high body fat, while someone with a normal BMI may still have health risks depending on body composition and lifestyle.
Calculate your BMI
How BMI is calculated
BMI uses a simple formula: weight divided by height squared. In metric units, BMI equals weight in kilograms divided by height in meters squared. In U.S. units, weight in pounds and height in inches are converted so the result matches the same BMI scale.
Example calculation
A person who weighs 180 pounds and is 70 inches tall has a BMI of about 25.8. This falls in the overweight range by standard adult BMI categories. That does not automatically mean the person is unhealthy; it simply means BMI should be viewed with other factors such as waist measurement, blood pressure, activity level, and medical history.
Related tools and guides
Frequently Asked Questions
Is BMI accurate?
BMI is useful as a broad screening tool, but it is not perfect. It does not distinguish fat mass from muscle mass.
Can athletes have a high BMI?
Yes. Athletes with more muscle can have a higher BMI even when their body fat is low.
Should children use this BMI calculator?
This calculator is intended for adults. Children and teens use age- and sex-specific BMI percentiles.
What should I do with my BMI result?
Use it as a starting point. If you are concerned, talk with a healthcare professional and consider other markers such as waist circumference, blood pressure, and lab results.
Does BMI diagnose obesity?
No. BMI categories are screening ranges. A diagnosis should come from a qualified healthcare professional.