How to Read Pet Food Labels: Guaranteed Analysis & Dry Matter Guide

When you flip over a can of wet cat food and a bag of dry dog kibble, their guaranteed analysis panels look completely contradictory. The dry kibble proudly states 30% crude protein, while the canned wet food only lists 10% crude protein.

At first glance, you might assume dry kibble has three times more protein than wet food. But that assumption is completely wrong.

Canned pet food is roughly 75% to 80% water. Once you remove all the water mathematically, that same canned food often provides 45% to 50% protein on a dry weight basis—substantially more than the dry kibble.

In this veterinary guide, you will learn how to decode guaranteed analysis panels, convert any pet food to a Dry Matter Basis (DMB), and calculate hidden carbohydrate percentages that manufacturers aren't required to print on the label.

1. What Is Guaranteed Analysis? (The "As-Fed" Trap)

Pet food regulations established by the Association of American Feed Control Officials (AAFCO) mandate that every commercial pet food package list four fundamental nutrient metrics:

1. 1
   Crude Protein (Minimum %)
2. 2
   Crude Fat (Minimum %)
3. 3
   Crude Fiber (Maximum %)
4. 4
   Moisture (Maximum %)

Some brands also voluntarily list Ash (mineral content such as calcium, phosphorus, and magnesium), which typically sits between 1.5% and 2.5% in canned wet food and 6.5% to 8.5% in dry kibble.

The critical catch is that these percentages represent the food as-fed—meaning the physical product inside the bag or can, water included. Because water contains zero protein, zero fat, and zero calories, high moisture severely dilutes the visible percentages on the label.

2. What Is Dry Matter Basis (DMB)?

Dry Matter Basis (DMB) is the universal scientific method veterinarians and animal nutritionists use to evaluate pet diets. By stripping out all water content mathematically, DMB evaluates food purely on its solid, nutrient-rich matter.

The 2-Step DMB Formula

Step 1: Calculate Dry Matter Percentage

Step 2: Convert Any Nutrient to Dry Matter Basis

Worked Example: Wet Food vs. Dry Food Comparison

Let's compare a standard canned pate against a standard adult dry kibble:

Once water is eliminated, the canned food actually delivers 45.5% protein compared to the dry kibble’s 31.1% protein.

3. How to Calculate Hidden Carbohydrates (The NFE Formula)

Have you ever noticed that pet food labels almost never list carbohydrate percentages? That is not an accident—pet food regulations do not require companies to disclose carbohydrates.

However, because animal food is composed of water, protein, fat, fiber, ash, and carbohydrates, you can calculate the missing carbohydrates using the Nitrogen-Free Extract (NFE) formula:

Once you have the as-fed carbohydrate percentage, convert it to Dry Matter:

*(Note: If ash is not printed on your can or bag, use 2.0% for wet food and 7.5% for dry kibble as veterinary standard estimates).*

4. What Are Ideal Carbohydrate Levels for Dogs and Cats?

For Cats (Obligate Carnivores)

Cats lack salivary amylase and have very low levels of intestinal and pancreatic enzymes needed to break down high starch loads. Their natural prey diet (mice, birds, insects) consists of roughly 50% to 60% protein, 35% to 40% fat, and less than 5% to 10% carbohydrates.

• •Optimal Feline Range: Under 10% to 12% DMB carbohydrates.
• •Diabetic Cats: Diets with under 10% DMB carbohydrates frequently allow diabetic cats to achieve complete clinical diabetic remission.

For Dogs (Adaptive Scavenging Carnivores)

During domestication alongside humans, dogs evolved multiple copies of the *AMY2B* gene, enabling them to produce more pancreatic amylase and digest cooked starches effectively.

• •Optimal Canine Range: 20% to 40% DMB carbohydrates for healthy, active adult dogs.
• •Low-Carb Canine Needs: Overweight dogs or dogs with insulin resistance often benefit from diets kept under 25% DMB carbohydrates.

5. Summary Checklist for Pet Parents

1. 1
   Never judge protein or fat from the front of the bag or raw percentages alone. Always calculate the Dry Matter Basis.
2. 2
   Beware of high-carb wet foods with gravy. Pates usually have minimal carbs (<10%), while sliced meats in thick gravies often use cornstarch, wheat gluten, or tapioca thickeners that push carbs above 25% DMB.
3. 3
   Use our free interactive tool whenever shopping for pet food or evaluating a prescription diet change.