Dry matter label math
Cat Food Carb Calculator
Use this cat food carb calculator to estimate carbohydrates from a guaranteed analysis label, convert the result to dry matter basis, and check whether the food is under 10% carbs before opening a low-carb wet food shortlist.
Estimate dry matter basis carbohydrates
Enter the percentages printed on the guaranteed analysis panel. Protein and fat are usually minimums, while fiber and moisture are usually maximums, so the result is a screening estimate rather than a lab analysis.
Formula and label limits
Carb formula
As-fed carbs are estimated as 100 - (protein + fat + fiber + moisture + ash). Dry matter basis then divides that as-fed result by the non-moisture portion of the food so wet and dry labels can be compared on the same basis.
When ash is missing
If the label does not list ash, the calculator uses ash=0 and marks the result as higher uncertainty. Enter ash when a label, typical analysis, or manufacturer page provides it.
Negative or rounded results
Guaranteed analysis values mix minimums and maximums, so label math can land below zero or near a threshold after rounding. Bowlly clamps negative as-fed carbs to 0% and shows dry matter basis to one decimal place.
Worked examples
Example wet label: protein 12, fat 5, fiber 1.5, moisture 78, ash 2 gives 1.5% as-fed carbs and 6.8% dry matter basis carbs. Without ash, the same label reads 3.5% as-fed and 15.9% DMB, so ash changes the screen.
Next action
After calculating, compare the result with the under 10% DMB screen and open the low-carb wet shortlist only as a label-reading starting point. Product fit still depends on calories, ingredients, phosphorus availability, palatability, and veterinary context.
Read the low-carb shortlist guideHow to use the result
Below 5% DMB
Very low by this label-math screen. Still compare ingredients, moisture, calories, and product fit.
5-10% DMB
Within the common under 10% carbs screening threshold used by many low-carb wet-food shoppers.
Above 10% DMB
Consider comparing other wet foods or asking the manufacturer for typical nutrient analysis values.
Frequently asked questions
How does this cat food carb calculator work?
It subtracts protein, fat, fiber, moisture, and ash from 100 to estimate as-fed carbohydrates, then removes moisture to calculate dry matter basis carbohydrates for easier wet-versus-dry comparison.
What if ash is missing from the label?
If ash is missing, Bowlly uses ash=0 and clearly marks the result as a higher-uncertainty estimate that may overstate carbohydrates. Enter ash when the label or manufacturer provides it.
Does under 10% carbs decide whether a food is right for my cat?
No. The calculator is a label-reading aid. Use it to prepare a shortlist and review health-adjacent feeding choices with a veterinarian who knows your cat.