Cat food calculator by weight and age — how much food does a cat of your cat's weight and age need? This guide is the calculator in words: the table for a cat at every weight from 2 kg to 11 kg, at every age from kitten to senior, plus worked examples that show how the numbers are used, and how to turn calories into cups and grams. The calculator is built from the resting energy requirement (RER) formula vets use, so every number can be checked: RER equals 70 times body weight in kg to the power of 0.75, and daily needs are the RER multiplied by the factor for the cat's age and activity.
The short version is: find your cat's weight in the left column, pick the column for its age, and read the calories. Then turn the calories into food with the cups and grams figures below, measure the food with scales, and adjust by body condition — you should be able to feel the ribs easily under a thin layer of fat and see a waist from above and from the side. Every figure is an estimate, and the right amount is the one that keeps weight steady. The cat food calculator does the same calculation for any weight and age, and the cat feeding chart by weight guide gives the same numbers in chart form.
Cat food by weight and age: the full table
Use the row nearest your cat's weight, then pick the column that matches the cat's age and activity. If your cat is between two rows, take the lower figure first: it is easier to add food to a cat that is losing weight than to take weight off a cat that has gained it.
| Body weight | Kitten (×2.5) | Adult, neutered indoor (×1.2) | Adult, intact (×1.4) | Active / outdoor (×1.5) | Senior (×1.2) |
|---|---|---|---|---|---|
| 2 kg | 295 | 140 | 165 | 175 | 140 |
| 2.5 kg | 350 | 165 | 195 | 210 | 165 |
| 3 kg | 400 | 190 | 225 | 240 | 190 |
| 4 kg | 495 | 240 | 275 | 295 | 240 |
| 5 kg | 585 | 280 | 330 | 350 | 280 |
| 6 kg | 670 | 320 | 375 | 405 | 320 |
| 8 kg | 830 | 400 | 465 | 500 | 400 |
| 11 kg | 1055 | 505 | 590 | 635 | 505 |
Note that calories are the real target and cups or grams are only a translation. Different foods have very different calorie densities, so always check the kcal per cup or per 100 g on your own bag or tin and work from that. A typical dry food is around 350 kcal per cup or per 100 g, and a typical wet food is around 70 to 100 kcal per 100 g — but your food may differ by a wide margin, and the bag's number always wins over this guide's.
Worked examples: how the calculator is used
Example 1 — a 4 kg adult cat. The RER for 4 kg is about 200 calories a day. Multiply by the factor for a neutered adult, 1.2, to get about 240 calories a day. That is roughly 0.7 cups or about 69 g of a typical dry food at 350 kcal per cup or per 100 g, split into two meals. If the same cat were intact, it would need about 275 calories; if it were very active, about 295; and if it were a senior, about 240.
Example 2 — a young cat. A kitten of 3 kg needs the RER for 3 kg, about 160 calories, multiplied by the young-animal factor — 2.5 — to get about 400 calories a day. That amount changes every two weeks as the young animal grows, because the weight changes, so the calculation must be repeated — and the young animal must be weighed every two weeks, so the weight used in the calculation is current. The kitten feeding schedule guide gives the schedule for young animals.
Example 3 — a senior cat. A senior cat of 8 kg needs the RER for 8 kg, about 335 calories, multiplied by the senior factor — 1.1 to 1.4 — to get about 400 calories a day. That is less than the same cat needed as an adult, because it moves less — but it still needs good protein to hold muscle, so a senior food, or an adult food fed in a smaller amount with your vet's agreement, is usually right. The how much food should a senior cat eat guide gives the calorie tables for senior cats by weight.
From calories to cups and grams
To turn calories into food, divide the daily calories by the kcal per cup or per 100 g on your own bag or tin. For a 4 kg adult cat needing about 240 calories a day, that is roughly 0.7 cups or about 69 g of a typical dry food at 350 kcal per cup or per 100 g. If you feed wet food, the same cat would need roughly 282 g of wet food a day, at 70 to 100 kcal per 100 g. Mixed feeding is fine as long as the total calories add up — the common mistake is to give a full measure of dry food plus a full tin or pouch of wet food, which roughly doubles the ration.
Measure food with scales or a measuring cup, not a mug or a handful. A 'cup' in one house can be half as much again as a cup in another, and that hidden extra is often the whole reason a cat is overweight. Weigh the daily amount once, note what it looks like in your cup, and use that cup every time. Treats count too: they should stay under 10% of daily calories, which for a 4 kg adult cat is under about 25 calories of treats a day. The treat calorie calculator works out what a treat is worth.
How age changes the calculation
Age changes the calculation in two ways: the factor, and the food. The factor changes because a young animal needs more calories per kilo than an adult, because it is growing, and a senior needs fewer, because it moves less. The food changes because a young animal needs a food labelled complete and balanced for kittens, an adult needs an adult food, and a senior usually needs a senior food, or an adult food fed in a smaller amount with your vet's agreement. Both changes should be made when the vet says the cat is ready, not at a birthday: a large breed takes longer to finish growing than a small one, and a senior's needs change when its body says so, not on a fixed date.
Age also changes what to watch: a young animal should be weighed every two weeks, because it grows fast, and an adult and a senior should be weighed monthly, because slow weight gain or loss creeps up unnoticed. A young animal that is not gaining weight, or a senior that is losing weight, needs a vet check — not just more or less food. The when is a cat considered a senior guide explains the senior boundary, and the how many calories should a cat eat per day guide gives the full calorie tables by weight.
When the calculator's number does not seem right
If the number in the table does not match your cat — the cat is gaining weight on the table's figure, or losing weight on it — the table is not wrong, but the factor is: your cat's activity, neuter status, or health is different from the table's assumption. A cat that is gaining weight on the adult figure needs the senior or weight-loss factor, or a smaller portion, and a cat that is losing weight on it needs a higher factor or a vet check. Weigh the cat monthly, feel the ribs, and look for a waist from above and from the side: you should feel the ribs easily under a thin layer of fat. If you cannot feel the ribs or there is no waist, the cat is probably overweight — cut food by about 10%, keep treats under 10% of daily calories, and ask your vet to set a target weight.
Do not feed by the bag's chart alone: bag charts are generous, because they are written for active animals and rounded up, so treat them as a maximum, not a target. And do not change the diet suddenly if the number seems wrong — change the amount by about 10%, wait a month, and re-weigh. Slow, measured change is how weight is managed safely. The cat ideal weight calculator gives a target weight range, and the feeding schedule generator builds a timetable from your cat's age and size.
For related reading, see the cat food calculator, the cat feeding chart by weight guide, the how many calories should a cat eat per day guide, the cat ideal weight calculator, the feeding schedule generator, the treat calorie calculator.
Frequently asked questions
How much food should a cat eat per day?
Find your cat's weight in the table above and read the calories for its age: a 4 kg adult cat needs about 240 calories a day. Turn the calories into food by dividing by the kcal per cup or per 100 g on your own bag or tin, measure with scales, and adjust by body condition and your vet's advice.
How do I work out food for my cat's exact weight and age?
Take the RER — 70 times weight in kg to the power of 0.75 — and multiply by the factor for your cat's age from the table above. Or use the cat food calculator, which does the same calculation for any weight and age, and the cat feeding chart by weight guide for the full table by weight.
How many calories does a kitten need?
Use the RER formula with a factor of about 2.5 for kittens, applied to the young animal's current weight and re-checked every two weeks as it grows. A food labelled complete and balanced for kittens is the right base.
How many calories does a senior cat need?
Older cats often need fewer calories — the ×1.1–1.4 range — because they move less, but they still need good protein to hold muscle. A senior food, or an adult food fed in a smaller amount with your vet's agreement, is usually right. If your cat has a health condition, ask your vet before choosing a special diet.
How do I convert calories to cups or grams?
Divide the daily calories by the kcal per cup or per 100 g on your own bag or tin. A typical dry food is around 350 kcal per cup or per 100 g, so a 4 kg adult cat needing about 240 calories needs roughly 0.7 cups or 69 g. A typical wet food is around 70 to 100 kcal per 100 g.
Why is my cat gaining weight on the calculator's amount?
Because the calculator's factor is a starting point, not a prescription for your individual cat: your cat's activity, neuter status, or health may be different from the table's assumption. Cut food by about 10%, keep treats under 10% of daily calories, and re-weigh in a month. If weight keeps rising, ask your vet to set a target weight.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.