BMI Calculator
Calculate your Body Mass Index (BMI) and see your weight category.
The Formula
Imperial:
BMI = (weight (lb) × 703) / height (in)²
= 70 / (1.75)²
= 70 / 3.0625
BMI = 22.86 — Normal weight
What Is BMI?
Body Mass Index (BMI) is a numerical value calculated from your weight and height. It provides a simple screening tool for weight categories — underweight, normal weight, overweight, and obesity — that may be associated with health risks.
BMI Categories (Adults)
Below 18.5: Underweight. 18.5–24.9: Normal weight. 25.0–29.9: Overweight. 30.0 and above: Obese. BMI is a screening tool, not a diagnostic measure — it does not account for muscle mass, bone density, age, or sex differences.
Frequently Asked Questions
What is a healthy BMI range?
For adults, 18.5 to 24.9 is considered the healthy range by the CDC and WHO. However, these are statistical guidelines — a person just outside this range may be perfectly healthy, while someone within it may still have significant health issues if they have high body fat and low muscle mass. BMI is a starting point for conversation with your doctor, not a definitive health verdict.
Is BMI accurate for athletes and muscular people?
No. BMI frequently misclassifies fit, muscular people as overweight or obese because muscle is denser than fat. Many elite athletes have BMIs in the 25–30 range despite very low body fat percentages. For athletes, body fat percentage measured via DEXA scan, hydrostatic weighing, or even skinfold calipers provides a much more meaningful assessment.
Does BMI differ by age?
For adults 20 and older, BMI uses the same categories regardless of age. For children and teens (ages 2–19), BMI is interpreted differently — it is plotted on age- and sex-specific growth charts as a percentile, since body composition changes significantly during development.
Is BMI different for different ethnic groups?
Yes. Research has shown that people of Asian descent have higher health risks at lower BMI thresholds. The WHO has proposed lower cutoffs for Asian populations — overweight starting at 23 and obesity at 27.5 rather than 25 and 30. Some health organizations have adopted these adjusted cutoffs in clinical practice.
What should I do if my BMI is in the overweight or obese range?
Talk to your doctor. A single BMI reading is one data point among many. Your doctor can evaluate additional factors like blood pressure, cholesterol, blood sugar, waist circumference, and family history to give you a complete picture of your health risks and appropriate next steps. BMI alone does not determine treatment.