Cup filler is the outlet that the coffee drips into the cup or pot, the amount of fillers does not determine the overall amount of coffee that can be made at once.
Larger machines can make up to 12 cups but can usually be set for smaller servings (can be multiple or single filler). Personal-size machines make up to four cups at a time (multiple fillers) and save counter space. Single-cup (single filler) machines are available, which, in many cases, brew directly into a travel mug for convenient on-the-road coffee consumption.