Cat Food Calculator
Daily calories and cups for cats from weight, life stage, and food energy.
What it does
Bag charts feed averages while vet math feeds the cat in front of you. Resting need scales with metabolic weight, 70 times kilos to the 0.75, then a life stage factor sets the day: 1.2 for the typical neutered adult. The tool above turns that into calories and cups from the bag label.
The default is a 4.5 kg neutered adult on 350 kcal per cup food. Resting need is 216 kcal, the day needs 260 kcal, and the bowl gets 0.7 cups. Imperial mode weighs 9.92 lb and lands on the same three figures through conversion.
Published factors back every option. Veterinary tables set neutered adults at 1.2, intact adults at 1.4, calm or obesity prone cats at 1.0, and growing kittens at 2.5. Weight loss runs near 0.8 of target weight and stays vet supervised. Resting need itself is the same 70 times metabolic weight across dogs and cats.
Charts start the conversation that ribs finish. Aim for a lean 4 to 5 of 9 body condition with ribs felt and waist visible, then feed the trend: gaining means less, ribby means more. Kittens, pregnancy, nursing, and illness all break the standard factors, so confirm those with a vet.
How to use
- Pick metric (kg) or imperial (lb).
- Weigh the cat at its ideal weight.
- Pick the closest life stage.
- Type the food energy from the bag in kcal per cup.
- Read daily calories first, cups beside them.
- Keep treats inside the total and reweigh monthly.
Formula
- RER
- Resting energy requirement in kcal per day.
- factor
- 0.8 loss, 1.0 calm, 1.2 neutered, 1.4 intact, 2.5 kitten.
- kcal/cup
- Metabolizable energy printed on the food label.
Use ideal weight, not current weight, for heavy or thin cats. The weight loss factor is a starting point for a vet plan, not a do it yourself diet.
Worked example
Example: 4.5 kg neutered adult
Metric defaults: 4.5 kg, neutered, 350 kcal/cup.
- Metabolic weight: 4.5^0.75 = 3.0897.
- RER: 70 x 3.0897 = 216.3, shown as 216 kcal.
- Daily: 216.3 x 1.2 = 259.5, shown as 260 kcal.
- Cups: 259.5 / 350 = 0.74, shown as 0.7 cups.
- Tool shows 260 kcal, 0.7 cups, 216 kcal RER.
Reference table
| Weight | Daily | Cups |
|---|---|---|
| 3 kg | 191 kcal | 0.5 cups |
| 4.5 kg | 260 kcal | 0.7 cups |
| 6 kg | 322 kcal | 0.9 cups |
| 8 kg | 400 kcal | 1.1 cups |
Limits
- Starting estimates, not prescriptions.
- Ideal weight assumed; adjust for condition.
- Needs swing widely around the figure.
- Vet decides illness, pregnancy, nursing, and weight loss rations.
Common mistakes
- Feeding current weight on an obese cat.
- Adding treats on top of the daily total.
- Guessing kcal per cup instead of reading the bag.
- Free feeding a weight loss case.
- Skipping monthly weigh ins while adjusting.
Try it yourself
Quick checks. Answers sit tucked under each question.
5 kg intact adult at 350 kcal/cup?
RER 234 kcal, daily 234 x 1.4 = 328 kcal, 0.9 cups.
3 kg kitten at 300 kcal/cup?
RER 160 kcal, daily 160 x 2.5 = 399 kcal, 1.3 cups.
9.92 lb neutered adult?
9.92 lb is 4.5 kg, so 260 kcal and 0.7 cups.
Questions
How much for a 4.5 kg adult?
260 kcal a day, about 0.7 cups at 350 kcal/cup.
What is RER?
Rest calories: 70 times kilos to the 0.75.
Neutered versus intact?
Factors 1.2 versus 1.4 of the same resting need.
How are cups found?
Daily calories divided by the bag kcal per cup.
Where do treats fit?
Inside the daily total, near 10% at most.
What about weight loss?
Near 0.8 of target weight resting need, run as a vet plan with monthly weigh ins.
Sources
- Ohio State Veterinary Medical Center: Companion Animal Nutrition Support
- Cornell Feline Health Center: Feeding Your Cat