To make it easier for you, we put the coffees that are served without milk in the same category. The smallest in volume is the ristretto: contrary to popular belief, this contains the least caffeine. The strongness of the coffee is determined by the duration of the extraction and the amount of ground coffee. Ristretto requires a minimum amount of preparation time. This is why it tastes weaker than espresso. Espresso is a simple black coffee, it takes more extraction time, and it is made of 7 g coffee per 40 ml. Doppio means a double shot of espresso. This type of black coffee is made of 14 g grounds, and in volume is twice as big as espresso. Because of that, we can call it the strongest. The lungo, alias long coffee, contains as much caffeine as espresso, but the extraction time is longer and more water is added. In cafés usually, we have to tell the waiter if we would like to drink any type of coffee out of this category with milk.