The quality score is calculated using a sophisticated algorithm that considers multiple parameters.

To simplify the explanation, the calculation is based on three (3) main criteria: (1) amount of protein (more is better), (2) amount of carbohydrates (less is better), and (3) quality and source of ingredients.
Based on those 3 main criteria, 9 score calculation rules are used to compare the different foods:

1. Amount and quality of carbohydrates (-)
2. Amount of protein (-)
3. Non-meat (plant or vegetable) protein (-)
4. Source of meat and fat ingredients (-)
5. Chemical additives (-)
6. An additional source of animal protein – location impact (+)
7. Quality and location impact of meat ingredients (+)
8. Natural source of taurine (+)
9. Chelated minerals (+)

(-) This rule deducts points
(+) This rule adds points

It is well known that the closer an ingredient is to the top of the ingredient list, the greater its relative weight and contribution to the food.

In general, dry cat food is composed of protein, fats, carbohydrates, fibers, vitamins, and minerals:

Protein

Protein is the most important component in a cat’s diet, and cats primarily get their protein from animal meat. Please read our article about it.

Fat

Fat is a primary source of energy and essential fatty acids.

Carbohydrates

Carbohydrates are controversial in a cat’s diet, as cats are obligate carnivores and typically consume very few carbohydrates.

Fibers

Fibers play an important role in digestion and food absorption, and vitamins and minerals are essential for different organism functions.

Dry matter values are used to compare the amount of nutrients in different cat foods. This means that moisture is excluded from the equation to provide a more accurate comparison.

Putting all of these and much more into a formula results in a product quality score.
The maximum score a cat food can receive is 100, and points are added or removed based on the score calculation rules.