How many calories does my dog need per day?

Resting energy requirement, often shortened to RER, estimates the calories a dog would burn simply existing at rest, and it scales with weight to the power of 0.75 rather than in a straight line, which is why doubling a dog's weight does not double its calorie need.

Multiplying RER by a factor between about 1.2 for a very sedentary dog and 2 or more for a very active or working dog gives the estimated daily calorie need, often called maintenance energy requirement.

A typical neutered adult pet dog getting regular walks usually falls around 1.6 times RER, while an intact adult often needs closer to 1.8, a sedentary dog closer to 1.2 to 1.4, and a very active or working dog anywhere from 2 to 5 depending on intensity.

Being honest about your specific dog's actual activity, not an idealized version of it, is the most important part of choosing where in this range to sit.

Once you have a daily calorie target, divide by your food's calories per 100g, then multiply by 100 to get the daily grams, always checking the actual number printed on your specific food's label.

Recalculate this whenever you switch foods, since calorie density differs meaningfully between brands and recipes, and a figure that was accurate for one product will not necessarily carry over correctly to another.