The number of calories in soy protein powder can vary depending on the brand and specific product. On average, one scoop (approximately 30 grams) of soy protein powder contains around 110-120 calories. However, some brands may contain more or less calories per scoop, so it's important to check the nutrition label of the specific product you're using. Additionally, calorie content can also vary depending on whether the soy protein powder is in isolate or concentrate form, as well as the presence of any added ingredients such as sweeteners or flavorings.