How do you fairly compare two kibbles sold at very different prices?
How do you fairly: Bring both foods to a common basis: composition on a dry-matter basis, energy density in kilocalories, then cost per daily serving. Comparing the bag price or the crude constituents leads to false conclusions, because water and energy concentration vary (AAFCO, 2024; FEDIAF, 2019).
General documentary information. For an individual animal, a veterinarian's advice takes precedence over any online content.
Putting the foods on a comparable basis
The first step neutralises water by reasoning on a dry-matter basis, which makes protein and fat percentages comparable (FEDIAF, 2019). The second step uses energy density to work out each food's real ration (AAFCO, 2024). The example that exposes the trap: a wet food shows an apparently low protein figure only because it holds a lot of water; converted to a dry-matter basis, its content can overtake a kibble's. Skipping this step is how shoppers reach exactly the wrong answer.
From the technical calculation to real cost
Once the rations are known, cost per day follows from combining the daily dose and the price (AAFCO, 2024). That figure, more telling than price per kilo, allows an honest comparison. What remains are the criteria no label can quantify: the maker's expertise, quality control and digestibility, to be requested from the manufacturer (WSAVA, 2021). A fair comparison therefore blends calculation with a judgement of how serious the company is.
| Step | Data used | Purpose |
|---|---|---|
| 1. Dry-matter basis | Analytical constituents, moisture | Compare the percentages |
| 2. Ration | Energy density (kcal) | Real dose |
| 3. Cost per day | Ration and price | Real spend |
Petipedia details the method for comparing on a dry-matter basis and by cost per serving, showing no prices and steering no purchase.
Sources
AAFCO, Calorie Content (2024); FEDIAF, Code of Good Labelling Practice (2019); WSAVA, Global Nutrition Guidelines (2021).