What are net carbohydrates? How to calculate them in dog food

Most dog food labels do not tell you the full story about carbohydrates. Many do not mention them at all. If you are trying to feed a low-carbohydrate or ketogenic diet, the number you actually need is net carbohydrates, and most brands do not make it easy to find.

Here is what net carbohydrates are, why they matter for dogs, and how to work them out for any food in about a minute.

What are net carbohydrates?

Net carbohydrates are the carbohydrates your dog's body can actually digest and turn into glucose. The formula is simple:

Total carbohydrates minus dietary fiber equals net carbohydrates.

Fiber, whether soluble or insoluble, is not fully digested. It passes through without raising blood sugar, so it is not counted. Starches, sugars and other digestible carbohydrates are counted.

Why net carbohydrates matter for dogs

Dogs have no nutritional requirement for carbohydrates. They make very little amylase, the enzyme that breaks down starch, and their metabolism is built to run on fat and protein.

When a dog eats digestible carbohydrates, blood glucose rises and the pancreas releases insulin to bring it back down. When that happens meal after meal, day after day, high carbohydrate intake has been linked to insulin resistance, weight gain and a higher risk of diabetes.

That is why net carbohydrates are the number that matters. Total carbohydrates include fiber that does not affect blood sugar, and sugar content alone leaves out starch, which makes up most of the carbohydrate in dry food.

For the bigger picture, see what the science says about carbohydrates in your dog's diet.

How to calculate net carbohydrates

If the label lists carbohydrates. Find total carbohydrates and dietary fiber, then subtract one from the other. For example:

• Total carbohydrates: 28g per serving
• Dietary fiber: 4g per serving
• Net carbohydrates: 28 minus 4 = 24g per serving

If the label does not list carbohydrates. This is the common case, because pet food labels are not required to show carbohydrate content. You can still estimate it from the guaranteed analysis printed on the bag:

1. Add together the percentages for crude protein, crude fat, crude fiber, moisture and ash.
2. Subtract that total from 100.
3. What is left is a rough estimate of the carbohydrate content.

For example, a dry food listing 26% protein, 16% fat, 4% fiber, 10% moisture and 7% ash adds up to 63%. Subtract that from 100 and the food is roughly 37% carbohydrate.

Two things to keep in mind. First, ash is not always listed. If it is missing, about 7% is a reasonable rough figure for most dry foods. Second, this method gives you total carbohydrates rather than net, because the guaranteed analysis lists crude fiber, which undercounts the total fiber in the food. It also gives a percentage by weight rather than by calories. None of that stops it from doing the job that matters: telling a genuinely low-carbohydrate food from a high one.

What to look for

A genuinely low-carbohydrate dog food should have net carbohydrates well under 5% of total calories, and ideally around 1% or less.

For comparison, most standard dry kibble is 30 to 60% carbohydrates by calories. Starch is what holds kibble together, and it is the cheapest ingredient in the bag.

Choose brands that state their carbohydrate content clearly. If a company calls its food low-carbohydrate but will not tell you the number, that is worth noticing.

Our own food is formulated to be under 1g of net carbohydrates per serving, and we print it.

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Waggy Tails,
Paul Raybould
Founder & CEO, Visionary Pet & KetoPet

This article is for general education and is not veterinary advice. Always consult a licensed veterinarian before changing your dog's diet, especially if your dog has an existing health condition.