BMI Calculator

Body Mass Index is a number derived from your weight and height that correlates with body fat levels across large populations. The formula is weight in kilograms divided by height in meters squared. In US units, BMI equals weight in pounds multiplied by 703, then divided by height in inches squared. For a 155 lb person at 5 ft 5 in, that is 155 times 703 divided by 65 squared, giving a BMI of 25.8. The CDC classifies results into four categories: Underweight (under 18.5), Normal weight (18.5 to 24.9), Overweight (25 to 29.9), and Obese (30 and above). These thresholds were established based on data linking BMI ranges to disease risk.

According to 2023 CDC National Health Statistics, the average BMI for American adults is 26.5 for women and 26.6 for men - both in the overweight range. Approximately 73.6 percent of American adults have a BMI of 25 or higher. Obesity rates have increased from 30.5 percent in 2000 to 41.9 percent in 2023. The CDC recommends adults with a BMI over 25 consult a healthcare provider about lifestyle interventions, and notes that losing just 5 to 10 percent of body weight produces clinically meaningful reductions in blood pressure, cholesterol, and blood sugar levels.

To lower BMI, you need to create a sustained caloric deficit. A 500-calorie daily deficit produces roughly 1 pound of fat loss per week. The most effective dietary strategy, according to 2024 NIH research, is reducing ultra-processed foods while maintaining adequate protein at 0.7 to 1 gram per pound of body weight. On the activity side, the CDC recommends 150 minutes of moderate aerobic activity weekly plus two strength training sessions. Muscle mass gained through resistance training raises your Basal Metabolic Rate, burning more calories at rest. Pair your BMI tracker with a BMR and TDEE calculator to set a precise daily calorie target. Use MyPlate.gov for free USDA nutrition planning resources.