About BMI
Body Mass Index (BMI) is calculated as weight (kg) ÷ height² (m²). It's used as a population-level screening tool to identify potential weight-related health risks.
BMI categories (CDC/WHO)
- Below 18.5 — Underweight
- 18.5–24.9 — Normal weight
- 25.0–29.9 — Overweight
- 30.0 and above — Obese
Limitations
BMI doesn't distinguish between fat and muscle, so athletes may register as "overweight" despite being healthy. It also doesn't account for where fat is distributed in the body. Always discuss weight and health with your doctor.
Frequently asked questions
How does this BMI calculator work?
The BMI calculator divides your weight by your height squared (kg/m²). Enter measurements in imperial or metric and it shows your BMI value and category — underweight, normal, overweight, or obese.
What is a healthy BMI range?
A BMI of 18.5–24.9 is considered normal weight for most adults. Below 18.5 is underweight, 25–29.9 is overweight, and 30 or above is obese, using CDC/WHO categories.
Is BMI accurate for everyone?
BMI is a screening tool, not a diagnosis. It does not distinguish muscle from fat, so athletes can read high, and it ignores fat distribution. Always discuss your health with a doctor.