Look at the guaranteed analysis on most dog food labels and you will find protein, fat, fiber and moisture, sometimes ash, but almost never carbohydrates. In the US, pet food regulations do not require carbohydrate content on the label. Yet many owners want to know roughly how much of a food is carbohydrate, whether because of a vet's recommendation or just curiosity. This guide shows how to estimate carbohydrates from the numbers that are listed, how to compare fresh food with dry food fairly, and what crude fiber really tells you. It is general label-reading information, not veterinary advice.
What the guaranteed analysis includes
The guaranteed analysis lists minimums and maximums:
- Crude protein (min)
- Crude fat (min)
- Crude fiber (max)
- Moisture (max)
- Sometimes ash (max) and other nutrients
"Crude" refers to the lab method, not the quality. Because these are minimums and maximums rather than exact values, any calculation from them is an estimate. Our guide to reading the guaranteed analysis covers the basics.
Estimating carbohydrates by difference
Carbohydrate is usually estimated "by difference": whatever is left after you subtract the other components from 100 percent.
Carbohydrate (approx.) = 100 − protein − fat − fiber − moisture − ash
If ash is not listed, many people use an assumed value. Ash in dog foods often falls in a range of a few percent to around 10 percent on a dry matter basis, depending on the food, so an assumption adds uncertainty. If you can find the brand's typical analysis or nutrient profile on its website, which sometimes lists ash and even carbohydrate directly, use that instead. See reading moisture and ash on labels.
Worked example (illustrative numbers)
Suppose a fresh food label lists: protein 10 percent, fat 6 percent, fiber 1 percent, moisture 75 percent, and the brand's site lists ash at 2 percent.
100 − 10 − 6 − 1 − 75 − 2 = 6 percent carbohydrate, as fed
That looks low, but most of the food is water. To compare with a dry food, convert to a dry matter basis.
Converting to dry matter basis
Dry matter basis removes water so you can compare foods with different moisture levels:
- Dry matter = 100 − moisture. In the example: 100 − 75 = 25 percent.
- Divide each nutrient by the dry matter and multiply by 100.
Carbohydrate on a dry matter basis = 6 ÷ 25 × 100 = 24 percent.
Protein on a dry matter basis = 10 ÷ 25 × 100 = 40 percent.
Do the same for a kibble. If a kibble lists protein 26 percent, fat 15 percent, fiber 4 percent, moisture 10 percent and ash 7 percent:
Carbohydrate as fed = 100 − 26 − 15 − 4 − 10 − 7 = 38 percent.
Dry matter = 90 percent; carbohydrate on a dry matter basis = 38 ÷ 90 × 100 ≈ 42 percent.
Now the two foods can be compared on the same footing. Our guide to comparing guaranteed analysis across brands uses the same method.
Calories from carbohydrate
Another way to look at it is the share of calories from each macronutrient. Protein, fat and carbohydrate supply different amounts of energy per gram, with fat supplying roughly twice as much as protein or carbohydrate. Some brands publish a calorie breakdown. If not, you can estimate it using standard energy factors, but because the label numbers are minimums and maximums, treat the result as rough. See reading calorie content.
Understanding crude fiber
Crude fiber is a lab measurement that captures only part of the fiber in food, mainly the less soluble components. It tends to underestimate total dietary fiber, which includes soluble fibers from ingredients such as pumpkin, beet pulp and psyllium. So:
- Two foods with the same crude fiber can have quite different total fiber.
- A low crude fiber number does not necessarily mean the food is low in fiber.
- Some brands publish total dietary fiber in their nutrient profiles, which is more informative.
Fiber can influence stool quality and how full a dog feels. If your vet has recommended a particular fiber level, ask the brand for total dietary fiber data.
Ingredients that contribute carbohydrates
The ingredient list gives clues about carbohydrate sources: grains such as rice, oats and barley; legumes such as peas, lentils and chickpeas; potatoes and sweet potatoes; and some vegetables and fruits. Ingredients are listed by weight before cooking, including water, so position in the list is only a rough guide. See reading dog food ingredient lists.
Keeping the numbers in perspective
Carbohydrate percentage alone does not make a food good or bad. Dogs can digest and use carbohydrates, and many complete and balanced diets contain them. Whether a lower or higher carbohydrate diet suits your dog depends on health, activity and your vet's advice. Questions about grain-free diets and heart health in particular should go to your vet; see grain-free diets and DCM questions.
Quick checklist
- Find protein, fat, fiber, moisture and ash (from the label or brand site).
- Estimate carbohydrate by difference.
- Convert to dry matter basis before comparing foods.
- Remember crude fiber underestimates total fiber.
- Use brand nutrient profiles when available; they are more precise than the label.
A simple spreadsheet helps
If you compare foods often, a small spreadsheet saves time. Make columns for protein, fat, fiber, moisture and ash as listed, then add formula columns for estimated carbohydrate as fed, dry matter, and each nutrient on a dry matter basis. Add a column noting where each number came from (label or brand website) and the date you checked, since recipes change. Once set up, you can paste in a new food in a minute and see it alongside the others on equal terms. Recheck the label when a bag or pack design changes, which is often a sign the formula changed too.
Common questions
Why don't labels list carbohydrates?
US pet food labeling rules do not require it. Some brands volunteer the information on their websites.
Is the estimate accurate?
It is approximate, because label values are minimums and maximums, and ash may be assumed. It is good enough to compare foods roughly, not for precise diet planning.
Can I use the recipe labels comparison for this?
Yes. It lists published label figures for several fresh recipes, which you can plug into the calculation.
About this guide
Our guides explain how to read labels, plans and specs so you can make your own choice with your vet. We don’t make health claims, we haven’t hands-on tested products, and we don’t publish invented statistics or ratings. Product facts come from official brand pages. How we work.
Product images are illustrative stock photos, not the exact products listed. Photo credits