BMI calculator

Body mass index (BMI) is a simple screening number that compares your weight to your height. It's calculated by dividing your weight in kilograms by your height in meters squared — the same formula this tool uses after converting your entries. If you prefer pounds and inches, the equivalent is your weight in pounds times 703, divided by your height in inches squared.

Because it only needs height and weight, BMI is easy to measure and is widely used by clinicians and public-health researchers to sort large populations into broad weight categories. It's a rough proxy for body fatness, not a direct measurement of it.

BMI can flag when weight may be worth a closer look, but it can't see the whole picture. It doesn't distinguish muscle from fat, so very muscular people — athletes, for example — can read as "overweight" while carrying little excess fat. It also says nothing about where weight sits on the body, and fat around the abdomen tends to carry more health relevance than fat elsewhere.

The same number can mean different things across ages, sexes, and ethnic groups. Older adults, people with more or less muscle than average, and some populations may have health risks that differ from what a single BMI figure suggests. Standard adult categories also don't apply to children, teens, or people who are pregnant.

Think of BMI as one data point among many — helpful for spotting a trend or opening a conversation, not for labeling your health. Measures like waist circumference, blood pressure, blood sugar, cholesterol, activity level, and how you feel day to day often tell a more complete story.

If your BMI is outside the range often described as healthy, that isn't a diagnosis. A licensed provider can interpret it alongside your history and goals and, if it makes sense for you, discuss options. FitRx offers a free eligibility check if you'd like to explore whether a personalized weight program may be a fit.