About PetCalculator.net

What This Site Is

PetCalculator.net is a free dog food portion calculator. You enter your dog's breed, weight, life stage, and activity level, select their food, and get a personalized daily calorie target and portion size in cups or grams. The math is based on the same RER/MER formulas used in veterinary nutrition practice.

That's it. No subscription, no account, no upsell.

Why I Built It

I'm Cobey, a software developer and dog owner. When I got Knight (my dog), I did what most people do: I looked at the back of the bag. What I found was a chart built for an average dog that bore no resemblance to Knight's actual weight, age, and activity level. The ranges were wide. The guidance was generic. And the more I dug into how dog calorie requirements are actually calculated, the more I realized the bag chart is a rough approximation at best and a sales strategy at worst.

So I built the calculator I wanted to exist. One that uses the actual veterinary formula, accounts for neuter status and activity level, and pulls the real caloric density from the food instead of a generic density estimate.

How the Calculator Works

The calculator uses two formulas standard in veterinary nutrition:

RER (Resting Energy Requirement): 70 × (body weight in kg)^0.75

This is the baseline caloric need for a dog at rest. The formula comes from established metabolic scaling research and is the foundation of the National Research Council's nutrient recommendations for dogs.

MER (Maintenance Energy Requirement): RER × multiplier

The RER is scaled by a multiplier based on life stage, neuter status, and activity level. The multiplier values used here are drawn from the NRC's Nutrient Requirements of Dogs and Cats (2006) and are consistent with the ranges published by AAFCO and referenced in veterinary nutrition textbooks.

The result is divided by the food's actual caloric density, sourced from the manufacturer's published nutritional data, to produce a daily cup or gram portion.

What that means in plain terms: the math behind this tool is not proprietary or invented. It is the same framework a veterinarian uses when calculating feeding amounts for a patient. The calculator applies it consistently, accounts for variables the bag chart ignores, and uses food-specific caloric data instead of a blanket density assumption.

The Food Database

The food database covers dry kibble and wet food products from major manufacturers. Every record includes:

• Caloric density (kcal per 100g and kcal per cup) sourced from the manufacturer's published nutritional information
• A last-verified date
• The region the product is sold in

No record is estimated or extrapolated from a competitor's data. If the manufacturer hasn't published caloric density, the product isn't in the database. When only one value is published, the second is derived using a documented conversion rather than a generic assumption.

The database is updated on an ongoing basis. If you find an error or a product that's missing, use the contact below.

What This Site Is Not

This is a calculation tool. It gives you a mathematically derived starting point based on established formulas and your dog's specific inputs. It is not veterinary advice, and it is not a substitute for your vet's guidance, especially for dogs with health conditions, unusual body composition, or specific medical dietary needs.

Every dog is different. The calculator gives you a number. Watch your dog's body condition over two to four weeks, adjust accordingly, and talk to your vet if something doesn't look right.

Contact

Questions, corrections, or missing foods: hello@petcalculator.net