The number of calories in casein protein powder can vary depending on the brand and formulation. On average, casein protein powder typically contains around 110-150 calories per serving. The calorie content of casein protein powder can be even lower in some brands, with some products containing as few as 80 calories per serving. Factors such as added sweeteners, flavors, and other ingredients can affect the calorie content of casein protein powder. It's best to check the specific product label for the exact calorie content.