Free tool
Cat food carb calculator
Carbohydrates are never printed on the label, but they can be calculated. Type in the guaranteed analysis from any cat food and get carbs on a dry matter basis instantly.
Try an example
Your result appears here
Enter the guaranteed analysis from the label, or try one of the examples above.
Tip: the guaranteed analysis panel is usually on the back or side of the can or bag.
How the math works
Pet food labels list protein, fat, fiber, moisture, and sometimes ash. Everything except carbohydrates. Because all components must sum to 100%, carbs are what remains:
carbs (as fed) = 100 − protein − fat − fiber − moisture − ash
As-fed numbers are misleading when comparing wet food (mostly water) with dry food. The dry matter basis removes the water so foods can be compared fairly:
carbs (DMB) = carbs as fed ÷ (100 − moisture) × 100
For cats with diabetes, veterinary guidelines (ISFM, AAHA) suggest carbohydrates under about 12% of calories, often quoted loosely as "under 10%". That target is a percent of calories, not dry matter. Dry matter basis is a convenient label-based proxy: for most foods, especially the higher-fat low-carb canned options, a result under about 10% dry matter sits comfortably within the calorie-based target. Wet food is generally preferred over dry. Every cat is different, so always confirm food choices with your veterinarian.
Common questions
Why are carbohydrates not listed on cat food labels? +
Pet food regulations only require the guaranteed analysis: protein, fat, fiber, and moisture (sometimes ash). Carbohydrates are everything left over, so they must be calculated by difference: 100 minus protein, fat, fiber, moisture, and ash.
What is dry matter basis (DMB)? +
Dry matter basis removes water from the comparison. A wet food with 5% carbs as-fed and 78% moisture actually has about 23% carbs once the water is excluded. DMB lets you compare wet and dry foods fairly.
What carb level is considered low for cats with diabetes? +
Veterinary consensus guidelines (ISFM and AAHA) state the target as carbohydrates under about 12% of calories, roughly 3 grams per 100 kcal. The popular "under 10%" figure also refers to percent of calories, not dry matter. This calculator reports a dry matter basis number because that can be worked out from any label without calorie data. The two are related but not identical, and a result under about 10% dry matter generally sits within the calorie-based target. This is general guidance only. Your veterinarian should confirm any food change for your cat.
What if ash is not on the label? +
Ash is often omitted. This calculator estimates 2.5% for wet food and 6.5% for dry food when it is missing, and marks the result as estimated. For exact numbers, contact the manufacturer.
Or just photograph the label
The Pawpoy app reads the label from a photo, runs this exact math, and explains how the food fits your cat specifically, ingredient warnings included. It's free in early access and we're onboarding gradually.