BMI Calculator
Calculate your Body Mass Index from height and weight, in metric or imperial.
Body Mass Index is a quick screening tool that relates your weight to your height, producing a single number used to broadly categorize weight ranges. It's a starting point for a conversation, not a diagnosis.
What the categories mean
The standard adult categories are: under 18.5 (underweight), 18.5-24.9 (normal weight), 25-29.9 (overweight), and 30+ (obese). These thresholds were developed from population-level data and are useful for large-scale screening, though they were never designed to assess any one individual's health with precision.
Where BMI falls short
BMI doesn't distinguish between muscle and fat — a muscular athlete can register as "overweight" despite having low body fat, since muscle is denser than fat. It also doesn't account for where fat is distributed on the body, age, sex differences in body composition, or bone density. Our Body Fat Calculator uses body measurements for a more direct estimate of composition.
Frequently asked questions
Is BMI accurate for athletes?
Not particularly — athletes and anyone with above-average muscle mass often show a higher BMI than their actual body fat percentage would suggest, since BMI can't distinguish muscle weight from fat weight.
Should I be worried if my BMI is in the \"overweight\" range?
BMI is one data point among many — waist circumference, body composition, blood pressure, and other health markers all matter. Discuss your specific situation with a doctor rather than relying on BMI alone.