How are the A to E grades on pet foods actually calculated?
These grades usually rest on an automatic scale applied to the printed composition: ingredient order, protein and carbohydrate levels, presence of additives (WSAVA, 2021). They do not measure real digestibility or quality control, and the scale itself varies from one site to the next.
General documentary information. For an individual animal, a veterinarian's advice takes precedence over any online content.
A scale built on the label
Most letter or point grades are computed by an algorithm that weights visible elements: the rank of the meat, estimated carbohydrate level, the type of additives, free-from claims (WSAVA, 2021). The calculation is reproducible but limited to what the label declares. The eye-opener: the same food can swing from an excellent to a poor grade depending on how heavily each scale weights one criterion or another.
What the scale cannot capture
The score measures neither real digestibility, nor raw-material quality, nor finished-product control, nor the maker's expertise (Tufts Petfoodology, 2023). The official FEDIAF and AAFCO nutrient profiles remain the only reference for adequacy (AAFCO, 2024). Understanding a site's scale, its criteria and their weightings, is necessary before granting a single letter any weight in a decision.
| Scale criterion | Source | Reliably measured? |
|---|---|---|
| Ingredient order | Label | Appearance only |
| Estimated carbohydrate | Calculation | Approximate |
| Digestibility, control | Absent | No |
Petipedia explains how rating scales work to put their results in perspective, without publishing any brand ranking.
Sources
WSAVA, Global Nutrition Guidelines (2021); Tufts Petfoodology (2023); AAFCO, Understanding Pet Food (2024).