What is BMI?
BMI (Body Mass Index) is a screening measure that uses your height and weight to estimate whether you are at a healthy weight. The CDC uses BMI to classify adults into weight categories: underweight, normal, overweight, and obese.
This US version uses pounds and feet/inches (the imperial system) for convenience. The BMI formula with imperial units includes a conversion factor of 703.
According to the CDC, 41.9% of American adults are obese (BMI 30+) and an additional 30.7% are overweight (BMI 25-29.9). Maintaining a healthy BMI reduces your risk of heart disease, type 2 diabetes, stroke, and certain cancers.
BMI has limitations — it does not account for muscle mass, bone density, body fat distribution, age, or gender. Athletes and muscular individuals may have high BMI despite low body fat. For a more complete picture, consider waist circumference (men under 40 inches, women under 35 inches) and body fat percentage.
Formula
BMI = (Weight in pounds / (Height in inches)²) × 703
Example — 160 lbs, 5'9": Height = 5×12 + 9 = 69 inches BMI = (160 / 69²) × 703 = (160 / 4761) × 703 = 23.6 (Normal weight)
BMI Categories (CDC/WHO): - Below 18.5: Underweight - 18.5 – 24.9: Normal weight - 25.0 – 29.9: Overweight - 30.0 – 34.9: Obese Class I - 35.0 – 39.9: Obese Class II - 40.0+: Obese Class III
Healthy weight ranges: - 5'4": 108–145 lbs - 5'6": 115–154 lbs - 5'9": 125–168 lbs - 5'10": 129–174 lbs - 6'0": 136–183 lbs
How to use this BMI Calculator?
1. Enter your weight in pounds. 2. Enter height in feet and inches. 3. See your BMI, category, and healthy weight range.
Note: BMI is a screening tool, not a diagnostic one. Consult your doctor for a complete health assessment.