How I Calculate Levels of Carbohydrates in Dry Dog Food

I selected the least and most expensive brands at my grocery store for a little experiment.


About the author: Emily Kane is a New Zealand-born animal behaviorist of the throw-back radical behaviorist type, albeit with a holistic-yuppie-feminist-slacker twist. She spent many years as an animal behavior researcher and is now more of an indoor paper-pushing researcher. Her early dog-related education came from Jess the Afghan Hound and Border Collies Bandit and Tam. It is now being continued by her own dogs and extended dog family and some cats (and her three aquatic snails Gala, Granny and Pippin — they think of themselves as dog-esque).

Working out carbohydrate levels of your dog’s kibble is harder than you think. Many people want to select diets that are lower in carbohydrates, but it is easy to be misled by brands that tout a fashionable lack of grains but that fill the product with other vegetable starches instead.

If you want to make a good guess as to which kibbles have less carbs, here’s what you do. Dog food labels all include a “guaranteed analysis,” which must state the percentage of the product that is made up of fat, protein, and water. You also need to take into account the “ash” content, which includes various minerals and other largely inert trace materials. Basically, the analysis involves burning the product up and whatever is left over is the ash. Ash content is usually not reported, so I would suggest that you estimate that it is about 10 percent of any dry dog food.

You can arrive at a rough estimate of carbohydrate content by subtracting the percentage that is fat, protein, water, and ash from the total, and assuming the remaining material is carbohydrate — keeping in mind that you are using a number of rough estimates here for a somewhat variable product. But in my opinion this estimate is good enough to compare different kibbles to see which has a lower overall level of carbohydrates.

As an example I selected the least and most expensive brands at my grocery store. (I don’t want to look like I am dissing or endorsing any given brand so I won’t give the names.)

Mainstream brands:

Brand 1:

  • Protein 18 percent
  • Fat 9 percent
  • Moisture 14 percent

100 – (18 + 9 + 14 + 10) = this product is approximately 49 percent carbohydrate.

Brand 2:

  • Protein 25 percent
  • Fat 14 percent
  • Moisture 10 percent

100 – (25 + 14 + 10 + 10) = this product is approximately 41 percent carbohydrate.

So it looks like mainstream brands fall at around 50 percent carbs. My goal is to find a product that gets me as close as possible to a low-carbohydrate diet (less than 30 percent, optimally closer to 10 percent). Given that it is hard to make kibble without some kind of carb to make a stable, dry product, this will probably mean just the lowest percentage I can get that I can afford.

In any case, 50 percent strikes me as too high. (After going through all the brands at the supermarket, the lowest barn value I found was in a mid-priced brand and was 36 percent. This has become my back-up brand for when I can’t get to the specialist pet food store, or an unexpected bill has put a squeeze on my budget.)

Next I turned to the top and bottom priced grain-free kibbles from the big box pet store.

Grain-free brands:

Brand 3:

  • Protein 23 percent
  • Fat 14 percent
  • Moisture 10 percent

100 – (23 + 14 + 10 + 10) = this product is approximately 43 percent carbohydrate.

Forty three percent is higher than some of the mainstream brands. So, “grain free” isn’t striking me as a terribly impressive claim, unless you think the dog’s wolf ancestors subsisted on roaming herds of wild sweet potatoes or you have a dog with issues specific to gluten rather than carbs in general. But some dogs do have sensitivities to specific ingredients, so you might want to pay attention to carbohydrates types, levels of fibers, calories, and other factors. Then if a food your dog does well with changes formulation or goes off the market, you have some idea what to look for as a replacement.

Brand 4:

  • Protein 34 percent
  • Fat 16 percent
  • Moisture 10 percent

100 – (34 + 16 + 10 + 10) = this product is approximately 30 percent carbohydrate.

That is pretty good, probably good enough for my purposes. It has become my “go to” brand.

Finally I also looked up some specifically low-carbohydrate brands online.

Low-carbohydrate brands:

Brand 5:

  • Protein 42 percent
  • Fat 18 percent
  • Moisture 10 percent

100 – (42 + 18 + 10 + 10) = this product is approximately 20 percent carbohydrate.

This brand actually provides a reported carb value of 18 percent. Which, given that my estimate is approximate, sounds about right.

Brand 6:

  • Protein 38 percent
  • Fat 20 percent
  • Moisture 10 percent

100 – (38 + 20 + 10 + 10) = this product is approximately 20 percent carbohydrate.

This brand provides a reported carb value of 17.5 percent.

Overall, mainstream brands are probably about 50 percent carbohydrate, but go as low as 36 percent for the brands I looked at. Grain-free brands may or may not be much lower than that depending on how they are formulated. Low-carbohydrate diets have about half the carbs, and they are probably going to come right out and tell you the percentage, so you don’t need to mess around trying to calculate it yourself.

Regardless of which diet you choose — or whether you go for a freeze-dried, wet, or raw diet instead — it is good to know as much as you can about what you are feeding your dog — without becoming obsessed. (Well, maybe just a little bit.)

Read more on feeding your dog:

3 thoughts on “How I Calculate Levels of Carbohydrates in Dry Dog Food”

  1. I’m not sure how accurate this calculation really is. I’ve reached out to several dog food manufacturers to compare their % carbs to what I calculated using the above formula and it is always significantly off. For instance, I researched a dog food with composition of 12.5% protein, 5.4% fat, and 71.63% moisture. According to the above calc is should be anywhere from 10.47 to .47 % carbs given the varying ash content (this is a canned food, so typically less than 10%). I contacted the company and was told the carb level falls at about 30%. Is the calculation different for dry and wet dog foods? If you ask me, the difference between calculated and “actual” are quite large especially when attempting to find a low carb food for a dog diagnosed with cancer. Did I miss the mark?

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