How many cat calories per day?
Type your cat’s weight and pick its life stage. The cat calorie calculator finds the resting energy requirement and multiplies it by the Merck Veterinary Manual factor, and can turn it into cups or cans of food.
- Calories per day
- 261
A 10 lb cat needs about 261 calories a day at 1.2 × RER.
- Resting energy (RER)kcal/day
- 218
- Life-stage factor
- 1.2
Calories per day: 261. A 10 lb cat needs about 261 calories a day at 1.2 × RER.
Calories per day by cat’s weight
How to calculate
Estimates a cat’s daily calories from its weight and life stage: the resting energy requirement 70 × kg^0.75 times the Merck Veterinary Manual factor.
Example with the default inputs (Cat’s weight 10 lb, Life stage Neutered adult (× 1.2)): A 10 lb cat needs about 261 calories a day at 1.2 × RER.
Method: RER = 70 × (body weight in kg)^0.75 kcal a day; calories per day = RER × the life-stage factor (neutered adult 1.2, intact adult 1.4, inactive or obesity prone 1.0, kitten 2.5); cups or cans = calories ÷ the food’s calories per cup or can.
- The factors are the Merck Veterinary Manual’s for healthy cats. Each cat differs, so the result is a starting point: weigh your cat every few weeks and adjust.
- For weight loss, ask your vet for a target weight and plan; this page does not give a weight-loss factor.
- Pregnant, nursing and sick cats need a vet’s plan. This page is for information only and is not veterinary advice.
Worked examples
Each example is checked against the calculator on every build.
- Cat’s weight 11.02 lb, Life stage Neutered adult (× 1.2) gives Resting energy (RER) 234.059107, Calories per day 280.870928.Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75; kittens 2.5 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals
- Cat’s weight 10 lb, Life stage Intact adult (× 1.4), Food calories per cup or can 400 gives Resting energy (RER) 217.569165, Calories per day 304.596831, Cups or cans per day 0.761492.Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75; kittens 2.5 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals
- Cat’s weight 3.307 lb, Life stage Kitten (× 2.5) gives Resting energy (RER) 94.87821, Calories per day 237.195526, Life-stage factor 2.5.Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75; kittens 2.5 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals
- Cat’s weight 2.205 lb, Life stage Inactive or obesity prone (× 1.0) gives Resting energy (RER) 70, Calories per day 70.Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75; kittens 2.5 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals
How it works
- Body weight in kg: a weight typed in pounds, ounces or grams is changed to kilograms (1 lb = 0.45359237 kg, 1 oz = 0.028349523125 kg).
- RER = 70 × (weight in kg)^0.75 kilocalories a day.
- Calories per day = RER × the life-stage factor:
| Life stage | Factor |
|---|---|
| Neutered adult | 1.2 |
| Intact adult | 1.4 |
| Inactive or obesity prone | 1.0 |
| Kitten | 2.5 |
- Cups or cans per day (when you type the food’s calories) = calories per day ÷ kcal per cup or can.
Rules
- Weight from 0.1 kg to 20 kg, both included. In pounds that is 0.2204622… lb to 44.092452… lb, so 0.23 lb is the smallest and 44.09 lb the largest two-decimal pound value accepted (0.22 lb is under 0.1 kg). Food calories from 1 to 2,000 kcal per cup or can; leave it empty to skip the portions.
- The result is a starting point for a healthy cat, not a prescription. Pregnant, nursing, sick or overweight cats need a vet’s plan.
Output format. Calories show as whole kcal a day, the factor with 1 decimal, and cups or cans with 2 decimals, each rounded half up.
Worked examples by hand
A 5 kg neutered adult. 5^0.75 = 3.34370. RER = 70 × 3.34370 = 234.06 kcal. × 1.2 = 280.87 kcal a day.
A 10 lb intact adult on 400 kcal-per-cup food. 10 lb = 4.5359237 kg; 4.5359237^0.75 = 3.10813. RER = 217.57 kcal; × 1.4 = 304.60 kcal a day; ÷ 400 = 0.76 cup a day.
A 1.5 kg kitten. RER = 70 × 1.5^0.75 = 70 × 1.35540 = 94.88 kcal; × 2.5 = 237.20 kcal a day.
A 1 kg cat, obesity prone. RER = 70 × 1 = 70 kcal; × 1.0 = 70 kcal a day.
Other questions people ask
How many calories does a cat need a day?
A 10 lb (4.54 kg) neutered adult cat needs about 70 × 4.54^0.75 × 1.2 = 261 kcal a day. An intact cat of the same weight needs about 305 kcal, and a 5 kg neutered cat about 281 kcal.
What is RER?
The resting energy requirement: the calories a cat burns at rest in a comfortable room. RER = 70 × body weight in kg raised to the power 0.75.
What factor should I use for my cat?
The Merck Veterinary Manual gives 1.2 × RER for a neutered adult, 1.4 × RER for an intact adult, 1.0 × RER for an obesity-prone cat, and 2.5 × RER for kittens (which can also be fed free choice).
How do I turn calories into food?
Find the kcal per cup or per can on the food label and type it. A 10 lb intact cat at 305 kcal a day, on dry food with 400 kcal per cup, needs 0.76 cup a day. Treats count too.
How do I feed a cat that needs to lose weight?
Ask your vet for a target weight and a plan. Weight loss in cats should be slow, and a cat that stops eating can become ill. This page does not give a weight-loss factor.
Why is the weight raised to the power 0.75?
Energy use grows more slowly than body weight: a cat twice as heavy needs about 2^0.75 = 1.68 times the calories, not twice as many.