Calories. One pint is equivalent to 16 fl. oz. A pint of draught Guinness contains 168 calories, and has a 4 percent alcohol content. Guinness extra stout has a 6 percent alcohol content and provides 235 calories per glass.ne pint of regular Guinness contains 13.3 g of carbohydrates. Guinness has zero fat grams and is also fiber-free. Although Guinness has been promoted as a rich source of iron, one pint contains just 1.1 mg.