If you’ve ever wondered why there are so many different grind types, it all has to do with the amount of time the grounds are will to be in contact with the water during the brewing process. Typically a finer grind is used for espresso, medium grinds for drip and etc.
The chart below demonstrates the type of grind to the type of device that is best used for the coffee. Keep in mind each type of grind and device provides a unique flavor profile and drinking experience.
Take for example, an extra fine grind is best used with an espresso machine. Espresso is typically served in 1-2 shots that have no more than 2 fluid ounces. While a coarse grind could be used for a French Press that yields anywhere from 1-8 cups. Then again, serving size is also relative to the actual device capabilities and usage. Keep in mind that having the proper grind for your device will make a world of a difference when making your coffee.