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How to Calculate Your Dog or Cat's Daily Food Portion

The feeding chart printed on a pet food bag is a rough average, not a precise number for your specific pet β€” here is the actual math behind how much a dog or cat needs to eat.

Resting Energy Requirement (RER): 70 Γ— (weight in kg)^0.75

RER estimates the calories an animal burns at complete rest. For a 10kg dog, that works out to roughly 70 Γ— 10^0.75 β‰ˆ 394 kcal per day, before any activity adjustment.

MER applies a multiplier for actual lifestyle

Maintenance Energy Requirement (MER) multiplies RER by a factor that varies by life stage and activity β€” commonly cited ranges are roughly 1.2-1.4x for a neutered, sedentary adult and higher for intact, active, or growing animals, and lower for weight-loss plans.

Convert calories to grams using the food's energy density

Pet food labels typically list calories per cup or per kilogram (kcal/kg). Dividing the day's target calories by that density converts the number into an actual gram or cup measurement to serve.

The bag's feeding chart is a generic starting point

Feeding guides printed on packaging are based on average animals within a weight range and often skew toward overestimating, since manufacturers tend to build in a margin for very active pets.

Treats count toward the daily total

A commonly cited guideline is keeping treats to no more than about 10% of daily calories, with the rest coming from a complete and balanced main food, so treat calories should be subtracted from the day's target.

Puppies and kittens need more per kilogram, not less

Growing animals have substantially higher energy needs relative to their body weight than adults, which is why growth-formula foods are denser in calories and fed on a different schedule.

Why the formula uses body weight to the 0.75 power

Metabolic rate does not scale in direct proportion to body weight β€” larger animals burn fewer calories per kilogram than smaller ones, a relationship described by an exponent close to 0.75 across many species. That is why simply doubling a dog's weight does not double its RER; it increases by a smaller factor.

Why the printed feeding chart is only a starting point

Breed, spay/neuter status, individual metabolism, and true activity level all shift real-world needs away from the average built into a bag's chart, sometimes substantially. Most feeding guidance recommends starting near the calculated or printed amount, then adjusting portions over a few weeks based on the animal's actual body condition.

Frequently Asked Questions

Should I follow the feeding chart on the bag exactly?

Treat it as a reasonable starting point rather than an exact prescription. Many pets do well on somewhat less than the chart suggests, and body condition β€” whether ribs are easily felt, waist is visible from above β€” is generally a more reliable ongoing guide than the printed number alone.

Does this replace advice from a veterinarian?

No β€” this is general information about how portion formulas work, not a substitute for professional advice. Pets with specific health conditions, extreme weight issues, or unusual activity levels should have their diet reviewed by a veterinarian.