Cat Food Calculator
Estimate a cat’s daily calories and grams of food using the energy density on its package.
Last updated · View algorithm, constants and default inputs (JSON)
About this calculator
Estimate daily calories from the selected life-stage factor, then convert them to grams using the food’s stated metabolizable energy in kcal/kg. Read the value from the package; energy density varies widely by product. This is a starting estimate, not an individual feeding prescription. Monitor body condition and ask your veterinarian to adjust it.
Worked example
calculated with the default values below
Body weight 9 lb · Life stage Neutered adult · Food energy on label 3,600 kcal/kg Food per day 67 g/day · Weight 4.08 kg · Daily calories 241 kcal/day · Food per day 2.4 oz/day
General background references
Disclaimer
These calculators offer general guidance and do not replace veterinary advice. Individual animals vary with breed, weight, health status and medication. Suspected poisoning from chocolate, medication, plants or chemicals is an emergency — contact your veterinarian or a pet poison control service immediately rather than relying on a calculator.
Implementation source
This record describes the implementation used by this page. It is not independent validation. External references, when available, support only the stated formula or definition; estimates and custom rules retain their own assumptions.
Formula and variables
RER = 70 × (0.45359237 × W)^0.75; kcal = RER × f; grams = kcal ÷ D × 1000
- W
- cat weight (lb)
- f
- selected life-stage factor
- D
- food energy density from package (kcal/kg)
- grams
- estimated food per day
The food amount uses the metabolizable energy printed on the package. Product recipes and individual needs vary; monitor body condition and ask your veterinarian to adjust portions.
Frequently asked questions
Why enter the food’s kcal/kg value?
Energy density varies by product and food type, so the calculator no longer assumes one fixed value for all dry, wet or raw food. Copy the metabolizable-energy figure in kcal/kg from the package. The gram amount is still only a starting estimate; adjust it with your veterinarian based on body condition and weight change.