About this site
Hi, I’m Josh. I run this site, and I check every formula and every page on it myself. It exists because the feeding information most owners rely on — the chart printed on the back of the bag — is a population average, not a plan for any individual animal.
Why I built this calculator
Feeding charts are built from the same energy equations used on this site, but they are written for a broad population and rounded upward. A chart cannot know that your dog is neutered, eight years old, and walks twice a day. The calorie figure printed on the packet is the number that lets you work out an amount for your own animal — so I built a calculator that shows its working instead of just handing you a number.
How the numbers are produced
Every calculation runs the same two-stage method used in veterinary nutrition:
- Resting Energy Requirement:
RER = 70 × (body weight in kg) ^ 0.75 - Maintenance Energy Requirement:
MER = RER × life-stage factor
The life-stage and activity factors follow the National Research Council’s Nutrient Requirements of Dogs and Cats (2006) and the WSAVA Global Nutrition Committee guidelines. The full factor tables are published on the calculator page, so you can check any result by hand.
How the content is checked
Formula values are checked against the published NRC and WSAVA references and cross-checked against several independent veterinary sources. Every calculation path is covered by an automated test suite that must pass before a new version goes live. Pages are reviewed and updated periodically.
What this site is not
This is an estimation tool, not veterinary advice. It does not diagnose or treat any condition. For anything specific to your pet — especially puppies, pregnant or nursing animals, and pets with a medical condition — please consult your veterinarian.
Contact
Email: contact@petportioncalc.com
Reviewed and updated: 2026-09-16