The perfect grind
The shorter the brewing process, the finer the grind. Different brewing methods have different grind requirements, so grind your coffee for the brewing method you use. The amount of time the coffee and water spend together affects the flavor elements that end up in your cup of coffee, and the design of your coffee maker dictates how long the coffee and water sit in direct contact during the brewing process. Coffee press, espresso machine, or drip coffee maker?
Choose the perfect grind...

The perfect grind for a coffee press
Choose a coarse grind if you're using a coffee press. The grind must be large enough so that the mesh filter can separate out the grounds. Because of the larger grind, the water and coffee are in direct contact for a bit longer than with other brewing methods – about four minutes.
For an espresso machine...

Espresso machine grind
Espresso machines are grind-sensitive and require a very fine grind, 30-35 seconds in a blade grinder. Slow and fast shots are often caused by a grind that is too fine or too coarse, frozen or refrigerated espresso beans and tamping coffee too hard or not firmly enough.
For a drip coffee maker...

Drip coffee maker grind
Drip makers perform best with either universal grind that is available in pre-ground coffees or with a grind specifically for a flat bottom or cone type filter. All Starbucks stores can grind coffee to this specification.
