Cat Food Carb Calculator (Dry Matter % Carbs)
Estimate carbohydrates from a food label (Guaranteed Analysis), then convert to dry matter for accurate wet vs dry comparison.
Quick answer
Two numbers matter
- As-fed carbs (%) = what you get from the label math
- Dry matter carbs (%) = best for comparing wet vs dry foods
Most labels don’t list carbs directly, so carbs are estimated “by difference.”
Guaranteed analysis
Enter label percentages (as-fed). If a field is unknown, you can leave it empty and use the “Estimate ash” switch.
Ash (minerals) (%)
Many labels don’t list ash. If you don’t know it, you can use an estimate.
If estimating, the calculator adjusts it by wet/dry style.
How to use this result
- Use dry matter carbs to compare wet vs dry foods fairly.
- Carbs are often estimated from label values. Small label rounding can change the final number.
- If your cat has diabetes or medical needs, follow veterinary guidance for diet selection.
How this calculator works (formulas)
1) Carbs “by difference” (as-fed)
Carbs% (as-fed) = 100 − (Protein% + Fat% + Fiber% + Moisture% + Ash%)
Labels often use rounding, so this is an estimate.
2) Dry matter percent
DryMatter% = 100 − Moisture%
3) Carbs on a dry matter basis
Carbs% (dry matter) = Carbs% (as-fed) ÷ DryMatter% × 100
This is the best number for comparing wet vs dry foods.
FAQ
Why doesn’t the label list carbs?
Many pet food labels list protein, fat, fiber, and moisture (and sometimes ash), but not carbohydrates directly. Carbs can be estimated by subtracting the listed components from 100%.
What is “dry matter basis”?
Dry matter removes water from the math so you can compare wet and dry foods fairly. Wet foods often look “lower” in carbs as-fed simply because they contain more moisture.
What if I don’t know ash?
You can estimate ash. This calculator uses a small default estimate (higher for dry food than wet food), but the result is still approximate.