Free BMI Calculator
Check your Body Mass Index (BMI) against standard medical health categories.
What is BMI?
Body Mass Index (BMI) is a simple medical screening tool used to broadly categorize human weight into varying health brackets: underweight, healthy weight, overweight, and obesity. The mathematical formula is derived entirely from mass and height and ignores all body composition variables like bone density and muscle mass.
BMI Categories & Thresholds
The World Health Organization (WHO) universally utilizes the following BMI thresholds for tracking general population health risks:
- Below 18.5: Underweight (Potential nutritional deficiency)
- 18.5 – 24.9: Normal / Healthy Weight
- 25.0 – 29.9: Overweight
- 30.0 and Above: Obese (Clinical risk category for metabolic disorders)
The Problem with BMI for Athletes
Because BMI strictly looks at height and weight, it is notoriously inaccurate for bodybuilders, athletes, and anyone who trains with weights. Muscle tissue is far denser than adipose tissue (fat). If you have a high amount of lean muscle mass, your BMI may classify you as "Obese" despite having a low body fat percentage and excellent cardiovascular health.
If you lift weights, we highly recommend using our Body Fat % Calculator or Lean Body Mass Calculator instead of BMI for an accurate picture of your health.