If you are planning on brewing a pot of coffee, you'll need a coffee filter. These are typically used to separate the ground coffee from the hot water. It has a mesh screen that sits on top of the coffee pot and prevents the grounds from getting into the coffee. To determine how many coffee filters you should use, you'll want to make sure you have enough for the entire pot of coffee. Be sure to measure how many cups of coffee you will be making. The number of cups will determine how many filters you'll need for your coffee. For example, if you are making a pot of 6 cups of coffee, you'll need 6 filters. If you are using a 12-cup coffee maker, you'll need 12 filters. This is one of the few instances where there is a definite answer.