How do I compare calorie density between two different dog foods for portioning?

Two foods can look similar in price, bag size, or ingredient quality but have meaningfully different calorie content per 100g, sometimes a difference of 50 to 100 kcal, which directly changes how much you need to feed.

Comparing serving size alone without checking calorie density can lead to accidentally over or underfeeding when switching between two different brands or formulas.

Write down the calories per 100g for both foods, then calculate the grams needed from each to hit your dog's same daily calorie target, which lets you see clearly how the two portions compare in actual bowl volume.

A higher calorie food gives a smaller, more compact portion, while a lower calorie food gives a larger portion for the same energy, which some owners prefer for dogs that seem to want more volume in the bowl.

When switching to a new food with a different calorie density, recalculate the daily gram amount from scratch rather than feeding the same weight you fed of the previous food.

Combine this calorie based calculation with a gradual transition over a week or more to reduce the chance of an upset stomach, and monitor body condition over the following few weeks to confirm the new amount is right for your dog specifically, rather than assuming the calculation alone guarantees the correct outcome without any follow up checking.