How much food is one portion for a cat? The answer depends on its weight, its age, and how active it is — and the way to work it out is resting energy requirement, or RER: RER equals 70 times body weight in kilograms to the power 0.75, and daily calories are RER multiplied by a factor for the cat's life stage. This guide is the cat food portion calculator in words: the formula, the portion sizes in cups and grams, and how many meals a day — so you can work out each portion without guessing. Every figure is an estimate, not a prescription: individual cats vary, and the vet's advice matters more than the formula. The cat food portion calculator does the same calculation for your cat's exact weight and stage.
The short version is: work out the daily calories, divide by the calories in the food, and split the result into meals. A typical dry food has about 350 kcal per cup or per 100 g, so a cat that needs 630 kcal a day needs about 1.8 cups or 180 g a day — and if it has two meals a day, each portion is about 0.9 cups or 90 g. A kitten needs three to four meals a day until about six months, then two meals a day, and an adult cat needs two meals a day. The cat food calculator guide gives the same method with the daily totals, and the cat calorie calculator guide gives the calorie tables by weight.
The cat food portion calculator formula
The formula is: RER equals 70 times body weight in kilograms to the power 0.75, and daily calories equal RER multiplied by a factor. The factor is about 1.6 for a neutered adult cat, about 1.8 for an intact adult cat, about 2.0 to 3.0 for an active cat, about 2.5 for a kitten, and about 1.2 to 1.4 for a senior. Then divide the daily calories by the calories in the food — which are printed on the bag or tin, usually as kcal per 100 g or per cup — and split the result into meals.
| Body weight | Neutered indoor (x1.2) | Intact adult (x1.4) | Active cat (x1.5) | Senior / weight loss (x1.2) |
|---|---|---|---|---|
| 2 kg | 140 | 165 | 175 | 140 |
| 3 kg | 190 | 225 | 240 | 190 |
| 4 kg | 240 | 275 | 295 | 240 |
| 5 kg | 280 | 330 | 350 | 280 |
| 6 kg | 320 | 375 | 405 | 320 |
| 8 kg | 400 | 465 | 500 | 400 |
Read the table from top to bottom and the pattern is clear: a cat's calorie needs rise with weight, but not in proportion — a cat that is twice as heavy does not need twice as many calories, because RER grows with weight to the power 0.75. A 5 kg cat needs about 280 kcal a day as a neutered adult, a 10 kg cat needs about 470 kcal, and a 20 kg cat needs about 795 kcal. The cat food portion calculator works out the exact figure for any weight and stage.
Worked examples: portions in cups and grams
A 4 kg neutered indoor cat needs about 237 kcal a day, which is about 0.7 cups or 68 g of a typical dry food with about 350 kcal per cup or per 100 g. If it has two meals a day, each portion is about 0.35 cups or 34 g. A 6 kg neutered indoor cat needs about 322 kcal a day, which is about 0.9 cups or 92 g a day, or about 0.45 cups or 46 g per meal if it has two meals a day. A 3 kg neutered indoor cat needs about 192 kcal a day, which is about 0.5 cups or 55 g a day, or about 0.25 cups or 27 g per meal if it has two meals a day.
Those are rough figures, because the calories in a food vary: a food with 400 kcal per cup needs less than a food with 300 kcal per cup, and a wet food has far fewer calories per gram than a dry food, because it is mostly water. Check the bag, and weigh the food — do not guess with a cup, because a cup of kibble can vary by a fifth depending on how full it is. The how much food should a kitten eat guide gives the calorie tables for young cats, and the senior cat diet guide covers feeding in the senior years.
How many meals a day
A kitten needs three to four meals a day until about six months, then two meals a day, and an adult cat needs two meals a day. A young animal's stomach is small, so it cannot eat enough in one or two meals to meet its needs, and it needs food little and often. An adult cat can be fed once or twice a day, but twice is better: it keeps the stomach from being empty for too long, and it gives the cat something to look forward to.
Split the daily amount evenly between meals, and do not add extra: a cat that gets two meals a day should get half its daily amount at each meal, not a full portion twice. Treats count, too: treats should be no more than a tenth of the daily calories, and a cat that gets a lot of treats needs less of its main food, or it will gain weight. The how often should you feed a kitten guide gives the feeding schedule, and the how many calories should a cat eat per day guide gives the calorie tables by weight.
Weighing portions: why a scale beats a cup
Weigh the food: a cup of kibble can vary by a fifth depending on how full it is, how big the kibbles are, and how the cup is filled, while a scale is exact every time. A cat that is fed by cup can easily get a fifth too much or too little, and a fifth too much every day adds up to a lot of extra weight over a year. A kitchen scale costs little, and it is the single best tool for keeping a cat at a healthy weight.
Weigh each portion, and write the amount down: a cat that is fed the same amount every day, weighed on a scale, will stay at a steady weight, and any change will be easy to spot. If your cat is gaining weight, reduce the food by a tenth and re-check in a month. If it is losing weight, increase the food by a tenth and re-check in a month. The cat weight loss diet plan guide covers a cat that needs to lose weight, and the how to help a cat gain weight safely guide covers a cat that needs to gain weight.
How to use the portion calculator
Use the calculator to get a starting point, then adjust by the scales and by feel: weigh your cat every month, feel its ribs and waist, and keep it at a body condition score of 4 or 5 out of 9. If your cat is gaining weight, reduce the food by a tenth and re-check in a month. If it is losing weight, increase the food by a tenth and re-check in a month. A cat that is at a healthy weight, eating a measured amount, and exercised every day, is a cat that will live longer and feel better.
Use the calculator to check the bag, too: if the bag says to feed much more than the calculator says, the bag is probably wrong for your cat — feeding guides on bags are often generous, because they are written for active cats and because the maker wants you to buy more food. Trust the calculator, the scales, and your vet, not the bag. The cat food portion calculator works out the exact figure for any weight and stage, and the cat calorie calculator guide gives the same method with more worked examples.
For related reading, see the cat food portion calculator, the cat food calculator guide, the cat calorie calculator guide, the how much food should a kitten eat guide, the senior cat diet guide, the cat weight loss diet plan guide.
Frequently asked questions
How much food is one portion for a cat?
It depends on its weight and its stage. Work out the daily calories — RER multiplied by a factor — divide by the calories in the food, and split the result into meals. A typical dry food has about 350 kcal per cup or per 100 g, so a cat that needs 630 kcal a day needs about 1.8 cups or 180 g a day, or about 0.9 cups or 90 g per meal if it has two meals a day. The worked examples above give the portions for several weights.
How many meals a day should a cat have?
A kitten needs three to four meals a day until about six months, then two meals a day, and an adult cat needs two meals a day. A young animal's stomach is small, so it cannot eat enough in one or two meals to meet its needs.
Should I weigh the food or use a cup?
Weigh it: a cup of kibble can vary by a fifth depending on how full it is, how big the kibbles are, and how the cup is filled, while a scale is exact every time. A kitchen scale costs little, and it is the single best tool for keeping a cat at a healthy weight.
Do treats count towards the daily amount?
Yes — a treat is food, and it counts. Treats should be no more than a tenth of the daily calories. A cat that gets a lot of treats needs less of its main food, or it will gain weight. Split the daily amount evenly between meals, and do not add extra.
How do I know if the portion is right?
Weigh your cat every month, feel its ribs and waist, and keep it at a body condition score of 4 or 5 out of 9. If your cat is gaining weight, reduce the food by a tenth and re-check in a month. If it is losing weight, increase the food by a tenth and re-check in a month.
When should I ask a vet about portions?
Ask your vet if your cat is losing or gaining weight on the calculated amount, if it is pregnant, nursing, ill, or recovering from surgery, or if it has a health condition that affects its diet. A vet can work out the exact amount for your individual cat.
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.