Cat Food Calculator Widget
Most cats eat a mix of kibble and wet food, which makes label portions hard to follow. This widget works out the cat's daily energy from weight and life stage, lets the reader choose how much comes from wet food, and returns grams or cups of dry food plus cans or pouches of wet.
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Adds a small script (what it does) that sizes the widget to fit its content, loads it lazily and keeps it isolated from your page's CSS.
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How it works
Energy at rest is 70 x (kg)^0.75, the same metabolic formula vets use for dogs, but the feline maintenance factors from the Merck Veterinary Manual are lower: 1.2 for a neutered adult, 1.4 intact, 1.0 for an indoor or gain-prone cat and 2.5 for kittens. A neutered 4 kg cat therefore needs about 238 kcal a day. The treat share (WSAVA suggests under 10%) is taken off first. The wet-food slider then divides the remaining calories: at 50% a 4.5 kg neutered cat with 5% treats gets about 124 kcal from kibble and 124 from cans. Dry food is converted with the label's kcal per kg or per cup, wet food with the kcal per can or pouch printed on it. Set the slider to 0 for dry-only feeding or 100 for an all-wet diet and the unused inputs disappear.
Calculation method
- RER = 70 x (body weight in kg)^0.75 kcal/day
- Daily energy = factor x RER: neutered 1.2, intact 1.4, indoor or obesity prone 1.0, kitten 2.5, or a custom factor
- Food kcal = daily energy x (1 - treat %); wet kcal = food kcal x wet share; dry kcal = food kcal - wet kcal
- Dry grams = dry kcal / kcal per kg x 1,000 (or cups = dry kcal / kcal per cup); cans = wet kcal / kcal per can
Worked examples
Neutered 4 kg cat on dry food only
Inputs: 4 kg; neutered; wet share 0%; 4,000 kcal/kg kibble; no treats
Result: 238 kcal a day; 59 g of dry food
70 x 4^0.75 = 198 kcal RER; x 1.2 = 237.6 kcal; / 4 kcal per g = 59.4 g.
Mixed feeding, 10 lb cat
Inputs: 10 lb; neutered; wet share 50%; 400 kcal/cup; 85 kcal pouches; treats 5%
Result: 261 kcal a day; 0.31 cups dry; 1.46 pouches wet; 13 kcal of treats
10 lb = 4.54 kg, RER 218 kcal, x 1.2 = 261; 95% of it split evenly gives 124 kcal each.
An informational estimate based on published guidance, not veterinary advice or a diagnosis. Every animal is different - ask your veterinarian about your pet's health, diet and care.
Limitations
- General maintenance factors only; not for pregnancy, nursing, illness or prescription diets.
- Label energy values and actual intake vary - weigh the cat monthly and adjust.
- Does not check the nutrient balance of a mixed diet, only its calories.
Where publishers use it
- A wet-food brand page showing how many pouches fit alongside a cat's usual kibble
- A feline clinic's weight-loss handout giving owners a calorie target and portion
- A cat-sitting service's feeding-notes page
- A kitten adoption pack from a shelter explaining kitten energy needs
- A pet nutrition blog comparing mixed feeding with dry-only diets
Questions
Why are cat factors lower than dog factors?
The Merck Veterinary Manual gives a neutered cat 1.2 x RER against 1.6 for a neutered dog. Neutered indoor cats are notably prone to weight gain, and an obesity-prone cat is fed at 1.0 x RER.
How do I split wet and dry food?
Decide what share of calories should come from wet food and type it in the wet-food box. 50% splits the food calories evenly; 25% gives a mainly dry diet with one small pouch. The widget divides the calories, not the weight, because wet food is mostly water and much less energy-dense than kibble.
Where is the kcal per can?
Pet-food labels state calorie content per kg and usually per can, pouch or cup. Always read your own product's label rather than guessing - energy differs a lot between recipes.
How many treats can a cat have?
WSAVA recommends that treats make up less than 10% of a cat's daily calories. For a cat needing 240 kcal that is under 24 kcal - often only a few treats.
Should I feed for my cat's current weight?
Only if that weight is ideal. For an overweight cat use the target weight from your vet; cats must lose weight slowly, because rapid weight loss can cause a serious liver condition (hepatic lipidosis).
What about kittens?
Kittens grow fast and the general factor is 2.5 x RER. Re-weigh every week or two and recalculate, because the amount rises quickly as the kitten grows.
Sources
- Nutritional Requirements of Small Animals - Merck Veterinary Manual . RER = 70 x (body weight in kg)^0.75; maintenance factors for dogs (intact 1.8, neutered 1.6, obesity prone 1.4, puppies under 4 months 3, over 4 months 2) and cats (intact 1.4, neutered 1.2, obesity prone 1, kittens 2.5). Checked 2026-10-01.
- Feeding treats to your cat (WSAVA Global Nutrition Toolkit) - World Small Animal Veterinary Association . Treats should make up less than 10% of a cat's daily calorie intake. Checked 2026-10-01.
Cite or recommend this tool
If you reference this tool in an article, course or documentation, these formats are ready to copy. They are optional - nothing is added to your site unless you paste it.
A2Z Tools Cat Food Calculator https://a2z.tools/embed/cat-food-calculator
<a href="https://a2z.tools/embed/cat-food-calculator">A2Z Tools Cat Food Calculator</a>
[A2Z Tools Cat Food Calculator](https://a2z.tools/embed/cat-food-calculator)
Cat Food Calculator by A2Z Tools - https://a2z.tools/embed/cat-food-calculator
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