* Different brands and formulas have different densities. A 44.1-ounce bag of kibble from one brand might be more dense than a 44.1-ounce bag from another brand, meaning it will have more kibble in the same volume.
* "Cup" measurements are not standardized for dog food. Dog food bags often use a "scoop" included in the bag for measuring, but this scoop may not be a standard cup.
To find out how many cups are in your bag, you'll need to refer to the bag's packaging. Most dog food bags will list a measurement conversion chart showing how many cups are in the bag.