Dog & Cat Food Calculator
How much to feed by species, weight and life stage, in cups and grams of your actual food.
https://calculators.nirajiitr.com/pets/pet-food-calculator
How it works
Resting energy requirement (RER) is what the body burns at rest. Energy use grows with body surface area rather than weight, which is why it is weight to the power of 0.75, not a straight multiple. A 40 kg dog does not need four times what a 10 kg dog does, only about 2.8 times. RER is then scaled by a factor for life stage and activity. Neutering, age and an indoor life all lower it, while growth and work raise it. Divide the daily calories by the kcal per cup or per kilogram on your food label to get the portion.
RER = 70 × (weight in kg)^0.75
daily calories = RER × life-stage factor- RER
- Resting energy requirement, kcal a day
- factor
- 1.6 for a neutered adult dog, 1.2 for a neutered adult cat
- kcal/cup
- Calorie density printed on the food label
Worked example
A 40 lb neutered adult dog on a kibble with 380 kcal per cup, allowing 10% of calories for treats.
- 1Weight in kg: 40 ÷ 2.2046 = 18.1 kg
- 2RER: 70 × 18.1^0.75 = 615 kcal
- 3Daily calories: 615 × 1.6 = 985 kcal
- 4From food, after treats: 985 × 0.9 = 886 kcal
- 5Cups: 886 ÷ 380 = 2.33 cups a day
About 2⅓ cups a day, split into two meals, with roughly 98 kcal left for treats.
Frequently asked questions
Why is this different from the feeding guide on the bag?
Bag guides are written for a broad range of dogs or cats, often intact and fairly active ones, and tend to run generous. Most pets are neutered and live indoors, which lowers their needs by 20–40%. Use this or the bag as a start, then weigh your pet every few weeks and adjust.
How do I tell if my pet is at a healthy weight?
Use a body condition score rather than the scale alone. You should be able to feel the ribs easily under a thin layer of fat without pressing, and see a waist from above and a tuck from the side. If you cannot feel ribs, cut portions by about 10% and recheck in a month. If ribs, spine or hip bones are visible, feed more and see a vet.
How many calories should come from treats?
The usual veterinary guidance is no more than 10% of daily calories. Treats are rarely complete and balanced, so going much higher starts to unbalance the diet as well as adding weight. Training treats count, as do table scraps and dental chews, which are often 70–100 kcal each for a medium dog.
Should I feed a puppy or kitten based on its adult weight?
No, use its current weight with the growth factor, and recalculate every couple of weeks as it grows. Young animals need two to three times their resting energy. Large-breed puppies should stay at the lean end of the range, because growing too fast raises the risk of joint problems.