Draft beer has a different flavor than bottled beer. Due to methods for processing and storage, draft beer retains more of the flavor gained through the brewing process. However, more than whether it comes from a bottle or tap, the type of beer and the amount of alcohol it contains determines the number of calories.
Calories in Alcohol
The primary factor that determines the number of calories in beer is the alcohol content. Alcohol contains a relatively high number of calories. At 7 calories per gram, alcohol is second only to fat, which has 9 calories per gram. In contrast, the two remaining calorie sources, protein and carbohydrates, each contain 4 calories per gram.
Types of Beer
Different types of beer vary in alcohol content, and so vary in calories. Stouts and ales, which can have alcohol content as high as 8 or 9 percent, have more calories, typically ranging in the 170 to 220 calories per 12-ounce serving range. Regular beer tends to have about 5 percent alcohol and usually has 140 to 170 calories per serving. Light beer has about 4 percent alcohol and averages 90 to 110 calories per serving. Certain high-alcohol content beers have 10 to 18 percent alcohol, and have over 320 calories per 12-ounce serving.
Most bottles contain 12 ounces of beverage, but most taverns serve draft beer in 16- or 20-ounce glasses, giving you more calories because of the larger serving size.