BMI Calculator
Body Mass Index is weight (kg) divided by height (m) squared.
Your measurements
BMI:
How BMI is calculated
BMI = weight (kg) ÷ height (m)². In US units, the equivalent formula is weight (lb) ÷ height (in)² × 703. BMI is a quick screening tool, not a diagnosis — it doesn't distinguish between muscle and fat, so very muscular people can register as "overweight" despite having low body fat, and it doesn't account for age, sex, or where fat is distributed on the body.
Frequently asked questions
What are the standard BMI categories? Underweight: below 18.5 · Normal weight: 18.5–24.9 · Overweight: 25–29.9 · Obesity: 30 and above. These thresholds are the same for adult men and women, though they were developed primarily from population-level studies and may not apply precisely to every individual.
Is BMI accurate for athletes or bodybuilders? Not particularly — since BMI can't tell muscle from fat, someone with a high muscle mass and low body fat can score in the "overweight" or "obese" range despite being lean and fit. Body fat percentage (see the Body Fat Calculator) is a better measure for muscular individuals.
Does BMI apply the same way to children? No — children and teens are assessed using age- and sex-specific BMI percentiles rather than the fixed adult categories used here, since healthy body composition changes significantly during growth.