A 1-ounce serving of boneless, skinless chicken breast contains approximately 31 calories. This makes chicken breast one of the leanest protein sources available. The exact calorie count can vary slightly depending on the specific cut and how it's prepared—raw chicken breast has about 31 calories per ounce, while cooked chicken breast (without added fat) typically has slightly higher calories at around 33-35 per ounce due to water loss during cooking. For context, a standard 3.5-ounce (100g) serving of cooked boneless, skinless chicken breast contains roughly 110-165 calories, depending on the cooking method. If you're tracking calories, remember that preparation matters: baking, grilling, or boiling without added fat maintains the lean profile, while pan-frying in oil or adding sauces will increase the calorie count. Chicken breast is valued in nutrition for its high protein content (about 7 grams per ounce) relative to its low fat and calorie content, making it a staple in calorie-conscious and high-protein diets.