Every dog food has something called the “Guaranteed Analysis” on the label. It’s the canine equivalent of the Nutrition Facts label you see on human foods. In short, the Guaranteed Analysis shows you the approximate protein, fat, fiber and moisture of the dog food.
However, most dog foods don’t show the percentage of carbohydrates on the Guaranteed Analysis. Carbs are a very important part of nutrition, especially for dogs, so how can you find out how many are in your dog’s food? Luckily, there’s a simple way to calculate the carbs.
Here’s the deal: We have already done all the work for you. Just check out our dog food reviews (in the section Nutrition). But if you want like to do it yourself, here’s how:
First things first. Your dog's food is made of protein, fat, carbs, ash and moisture. What’s ash? It’s essentially the total bone and mineral content of the food.
From the Guaranteed Analysis section of the food label you can see the protein, fat, ash and moisture. To get to carbs, we simply subtract them from the total, like this:
Carbs = 100% - Protein - Fat - Ash - Moisture
Let’s assume the Guaranteed Analysis shows the following on the food label for a wet food:
Ash is often not shown on the food label, but you can use an estimated amount of 7% for dry dog foods and 2% for wet foods. Let's use 2% in this example. Foods with about 10% moisture are dry foods and around 80% moisture shows you it's a wet food. So this one is a wet food. Note: to calculate carbs, we ignore the fiber because fiber is a part of the carbs. Let's try it:
Carbs = 100% - 11% - 5% - 2% - 78% = 4%
So the carbs in this example would be 4%. Pretty low, right? Not necessarily. So far, we've only seen half the story. So now that we know the carbs, let’s talk about the moisture in your dog’s food and how it changes everything!
Different dog foods contain a different amounts of water. Many wet foods, for example, consist of 75% water, while many dry foods only have about 10% water. Because of that, the Guaranteed Analysis doesn’t let you to objectively compare wet and dry foods - the percentages of their dry nutrients, by comparison, are skewed because of the different moisture percentages. So on the surface, wet foods will often look like they have a lot fewer protein, fat and fiber than dry foods - which isn’t always true.
But there’s an easy solution! Enter the “dry matter basis” - it’s a simple calculation that removes all moisture from the food, so that you can compare the actual nutrition values between wet and dry foods.
For your convenience, we have calculated the dry matter basis for 3,000+ dog foods already. You can see them in the “Nutrition” section of each of our dog food reviews.
If you want to give the dry matter basis calculation a try yourself, here’s how to do it:
Look at the Guaranteed Analysis on the dog food label. Let’s say it’s a dog food that shows:
Carbs 4% (calculated above)
Next, use the following formula to remove the moisture from the numbers:
Dry Matter Basis = (Original Number / 100% - Moisture) * 100
When we apply that, our numbers become:
Wow, the numbers suddenly look very different, don't they? After absorbing the water, these are the real, solid macro-nutrients your dog actually gets from this wet food. Note: Moisture becomes 0%, of course, when removing it -no need to calculate that.
As you can see, calculating out the moisture is really important to compare foods with different water content. So always check the dry matter basis to prevent your nutrient numbers from being watered down… And now you know how! As mentioned, we've already done all these calculations for you in all of our dog food buying guides.
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