How much should I feed my pet?

The short answer

The feeding guide on the bag is a reasonable starting point, but it's calibrated for an average pet of a given weight, not for your specific animal. Individual factors like neuter status, age, activity level, and body condition all shift energy needs significantly. Most pets benefit from portions that are adjusted every few weeks based on body condition, not set once and forgotten.

Two standard calculations form the foundation: Resting Energy Requirement (RER) and Daily Energy Requirement (DER). Understanding these helps you interpret the bag guide, communicate with your vet, and make adjustments when your pet's condition changes.

Why the bag guide is a starting point, not a prescription

Feeding guides on pet food packaging are typically calculated for an intact adult dog or cat at average activity, with no adjustments for neuter status, breed size variation, or individual metabolic differences. A neutered 10 kg dog has meaningfully lower calorie needs than an intact 10 kg dog at the same activity level, yet both may get the same bag recommendation.

Research from the NAVC and AAHA has consistently found that pets fed according to bag guidelines without body condition monitoring tend toward overfeeding over time. Free feeding amplifies this: studies indicate that pets with continuous access to food consume roughly 15 to 20% more than those on portion-controlled schedules. Multiple people in a household feeding the pet independently is one of the most common drivers of unintentional overfeeding.

Step 1: Calculate resting energy requirement (RER)

RER is the energy your pet needs at rest, in a comfortable temperature, not including activity or digestion. It's the metabolic floor. For dogs and cats, the formula is:

For example, a 10 kg dog: 70 x (10)^0.75 = 70 x 5.62 = approximately 394 kcal/day as RER. A 5 kg cat: 70 x (5)^0.75 = 70 x 3.34 = approximately 234 kcal/day as RER. These are estimates, not targets. Use them as a foundation for the next step.

Step 2: Apply the life stage factor to get DER

Daily Energy Requirement (DER) is calculated by multiplying RER by a life stage factor that accounts for activity, reproductive status, and age. The NAVC coursework and Pet Nutrition Alliance provide the following reference factors:

• Neutered adult dog: RER x 1.6
• Intact adult dog: RER x 1.8
• Weight loss (dog): RER x 1.0
• Senior dog: RER x 1.4
• Puppy (up to 4 months): RER x 3.0
• Puppy (4 months to adult size): RER x 2.0
• Neutered adult cat: RER x 1.2
• Intact adult cat: RER x 1.4
• Active cat: RER x 1.6
• Kitten (growth): RER x 2.5

Using the 10 kg neutered dog example: DER = 394 x 1.6 = approximately 630 kcal/day. Divide that by the kcal/cup listed on the food bag (usually found in the guaranteed analysis or feeding guide) to get the daily cup amount.

Step 3: Adjust based on body condition score

No formula is a substitute for observing your pet's actual body. The 9-point Body Condition Score (BCS) scale from AAHA is the standard tool. An ideal BCS is 4.5 to 5 out of 9, corresponding to 15 to 25% body fat. At this score, you can feel ribs easily when you run your hands along the sides, but they're not visibly prominent. There's a visible waist from above and an abdominal tuck from the side.

If your pet's BCS is 6 or 7 (overweight), consider reducing the calculated DER by approximately 20 to 25% and reassessing monthly. If BCS is 3 or below (underweight), increase portions gradually and check with your vet to rule out underlying health issues. Body weight on a scale matters less than BCS: a muscular dog at a higher weight may have a healthier BCS than a lighter dog with poor muscle mass.

A note on cats

Cats require more protein per kilogram of body weight than dogs because they are obligate carnivores with permanently active protein metabolism pathways. Their DER calculations use different life stage factors (neutered cat = 1.2 x RER, not 1.6 like a neutered dog). Portion reductions for weight loss in cats should be gradual, as rapid caloric restriction in cats can cause hepatic lipidosis (fatty liver disease), a serious condition.

For cats on a weight loss plan, a reduction of no more than 20% below the current intake, with monthly BCS checks, is generally the evidence-based approach. Consult your vet before placing a cat on a weight loss program.

Free feeding vs. portion-controlled feeding

Free feeding (leaving food available all day) is generally not recommended for dogs. Research consistently shows 15 to 20% overconsumption with free feeding compared to scheduled meals. For dogs, two measured meals per day is a practical and evidence-based approach.

For cats, particularly those in multi-cat households, the picture is more nuanced. Some cats self-regulate well; others do not. If your cat tends toward overconsumption, portion-controlled feeding with two to three meals per day is a reasonable strategy. Automated feeders can help in households where owners have variable schedules.

Content based on NAVC Pet Nutrition Coach Certification coursework and AAHA Nutritional Assessment Guidelines.

KibbleLab Explains articles are educational, and are not veterinary advice. Before starting an elimination diet, a weight plan, or any major diet change, talk to your veterinarian.