How Long Does a Bag of Dog Food Last for a Dog?

It's a common fact that buying in bulk saves money long-term. When buying dog food, though, determining how long a bag of food will last can be a challenge. If you purchase too much food, the kibble may go rancid before your dog is able to eat it. If you buy too small of a bag, your pup may need food more frequently than you'd like to buy it. Consider factors such as your dog's size, the quality of the ingredients and your dog's metabolism when trying to decide how long a bag of food may last your four-legged friend.

While this may seem obvious, the bag's size definitely matters when it comes to how long the dog food will last for your dog. However, bigger isn't always better. The longer it takes your dog to go through the bag of food, the more likely it is that the food will go bad before your pup is able to enjoy it. Dog food is purchased by weight, and common weights of bags range from 5 to 30 or 40 pounds. You should choose the size of bag that your dog can eat in a month.

Bigger dogs tend to eat more than smaller dogs. When attempting to determine how long a bag of food will last for your dog, always work with an accurate weight. Always check the back of the bag for feeding guidelines and recommendations, but generally, the bigger the dog, the more dog food you're going to need.

On the back of every bag of dog food there's a chart that provides recommendations on how much food your dog will need to eat. Once you find the category corresponding with your dog's weight and age, you'll find a range, such as 1 to 3 cups of food per dog per day. Every dog is an individual and will require differing amounts of food to maintain his weight. The more physical activity your dog participates in or the higher metabolism your dog has, the more food your pup will need.

The more nutritional punch a kibble packs, the less you'll need to feed to ensure proper growth, health and weight maintenance. For example, if you're feeding a kibble full of fillers and meat byproducts, you may need to feed your 50-pound dog 4 cups a day. If feeding a kibble with meat as the first three ingredients, followed by eggs, then by single-source grain, you may only need to feed the same dog 2 cups of food a day. The fewer cups a day you need to feed your dog, the longer a bag of food will last.

According to the Dog Food Project, most brands of kibble contain 4 to 5 cups of food per pound. If you have a 65-pound dog with an average level of activity and metabolism, your dog may eat 4.5 cups of a generic brand and 2.5 cups of a high-quality brand a day. If feeding a generic brand, you'll go through roughly a pound of food a day, thereby needing a 30- to 40-pound bag of food a month. If feeding a high-quality brand, you'll go through roughly half a pound of food a day, thereby needing a 15-pound bag for a month. To do the math for yourself, simply multiply the weight of the bag times 4 cups, to be conservative, and then divide the total by the feeding recommendation on the back of the bag for your dog's weight.