Packet guidelines are written for the average pet — yours may need more or less. This calculator estimates your dog’s or cat’s daily energy needs from their weight and life stage, then converts it into cups of food per day. The result updates live as you type.
The formula behind the calculator
Veterinary nutritionists estimate energy needs in two steps. First, the resting energy requirement (RER) — the calories a pet burns at rest:
RER = 70 × (weight in kg)0.75
Then the daily energy requirement (DER) multiplies RER by a factor for life stage and activity:
DER = RER × life-stage factor
| Life stage / activity | Factor |
|---|---|
| Puppy / kitten under 4 months | 3.0 |
| Puppy / kitten 4–12 months | 2.0 |
| Adult, intact | 1.8 |
| Adult, neutered | 1.6 |
| Senior (7+ years) | 1.4 |
| Very active / working | 2.5 |
| Weight loss | 1.0 |
Finally, cups per day = DER ÷ kcal per cup of your pet’s food.
Assumptions
- Weight is converted at 1 kg = 2.20462 lb.
- Neutered pets need roughly 10–20% fewer calories than intact pets of the same weight.
- The default 350 kcal per cup suits many dry dog foods; always use your packet’s figure — foods range from about 250 to 500 kcal per cup.
- This is a starting point: adjust up or down if your pet gains or loses weight over 2–4 weeks.
Sources
- National Research Council — Nutrient Requirements of Dogs and Cats (National Academies Press)
- The Ohio State University College of Veterinary Medicine — resting and daily energy requirement guidance
- World Small Animal Veterinary Association (WSAVA) — Global Nutrition Guidelines
Frequently asked questions
Why does the calculator ask for kcal per cup?
Foods vary enormously in energy density — a “light” food might have 280 kcal per cup while a performance food has 480. Two cups of one food can equal three cups of another, so the packet figure is essential for an accurate portion.
How many meals a day should my pet have?
Most adult dogs and cats do well on two meals a day. Puppies under 6 months usually need three or four smaller meals, and some cats prefer several small meals — split the daily total accordingly.
Should I follow this or the packet guidelines?
Use this calculator as your tailored starting point, since it accounts for your pet’s actual weight and life stage. Then watch their body condition over a few weeks and adjust — no formula beats weighing your pet regularly.
Can I use this for wet food?
Yes — enter the food’s energy as kcal per tin or pouch instead of per cup, and read the result as tins or pouches per day rather than cups.
My pet is gaining weight on this amount. What now?
Cut the portion by about 10% and reassess in two to four weeks. If weight keeps climbing, or your pet seems unusually hungry or lethargic, ask your vet to rule out medical causes before cutting further.
This tool gives estimates for guidance only and is not veterinary advice. Individual needs vary — your vet can fine-tune portions for your pet.
Keep reading: browse our Guides hub for more step-by-step help with feeding and nutrition.