Food amount calculator
How much should your cat eat? The right amount depends on energy needs — on weight, neutering and life situation. The calculator estimates the daily requirement in calories and converts it into grams of wet or dry food.
How the calculation works
How much your cat should eat does not depend on a fixed number of grams but on its energy requirement. That is calculated in two steps: first the resting energy requirement (RER), which rises with weight — the formula is 70 × body weight0.75. We then multiply this value by a factor for the life situation (MER), because a neutered indoor cat needs considerably less than a growing kitten. From the resulting calorie requirement we derive the daily amount in grams via the energy density of the food.
Why the packaging often says something different
Manufacturer recommendations are rough averages for a "normal" cat. The actual requirement depends on neutering, activity, age and metabolism — two cats of the same weight can differ by 20–30%. The most important control value is therefore not the calculator but your cat's figure: the ribs should be easy to feel but not visible, and a slight waist should be recognisable from above.
Energy requirement by life situation
| Life situation | Factor | Note |
|---|---|---|
| Kitten (growth) | 2.5 × RER | high requirement, several small meals |
| Adult, neutered | 1.2 × RER | the most common case — prone to overweight |
| Adult, intact | 1.4 × RER | slightly higher basal metabolism |
| Weight loss | 0.8 × RER | calculate for the target weight, reduce slowly |
Guideline values. Very active outdoor cats sit higher, dedicated couch cats lower.
Wet or dry food — the big difference
When converting to grams, energy density is decisive, and it differs enormously: wet food contains a lot of water and typically provides only about 80–90 kcal per 100 g, while dry food packs around 350–400 kcal per 100 g. The same cat therefore needs roughly four to five times the amount of wet food compared to dry food. You find the exact value (kcal/100 g) on the packaging under analytical constituents or the feeding recommendation — if it deviates a lot, calculate with the value of your specific food.
Wet food has one big advantage: its high water content supports the fluid intake that is so important for cats and helps prevent urinary and kidney problems. Many owners therefore feed wet food as the base and use dry food only as a small supplement or in puzzle toys.
Do not forget the treats
Treats and snacks count fully towards the daily ration and are easily underestimated — they should make up at most 10% of daily calories. If you train or reward with a lot of snacks, subtract the corresponding amount from the main meal, otherwise weight gain is guaranteed.
How to use the calculator
- Set your cat's current weight (for weight loss, the target weight).
- Choose the matching life situation — the most common case is "neutered".
- Choose the food type and read off the calorie requirement and daily amount in grams.
- Split the amount into two meals (more for kittens) and check your cat's figure after 2–3 weeks.
The calculator provides a starting value for healthy cats. For kittens, pregnancy, illnesses (e.g. kidney disease, diabetes) or underweight, agree the ration with your vet or a certified nutrition consultant.
How often to feed per day?
Cats are natural snackers who, in the wild, hunt many small mice spread across the day. Two meals are the minimum; several small portions or an automatic feeder are ideal. Kittens need three to four meals. Fresh water should always be available — ideally somewhere other than next to the food, as cats instinctively prefer that.
Keep an eye on the weight
Overweight is the most common nutrition problem in indoor cats and promotes diabetes, joint and liver disease. Weigh your cat regularly (a bathroom scale with and without cat on your arm is enough) and adjust the amount as needed. The cat age calculator shows you how old your cat is in human years and which life stage it is in; you can estimate the running food and husbandry costs with the cat cost calculator.
Frequently asked questions
How much should my cat eat per day?
That depends on energy needs, not a fixed number of grams. A neutered 4 kg indoor cat needs roughly 200–220 kcal per day — depending on the food about 230–260 g of wet food or around 55 g of dry food.
Why does my cat need much more wet than dry food?
Wet food is mostly water and provides only about 80–90 kcal per 100 g; dry food packs around 350–400 kcal. For the same calories a cat therefore needs four to five times the amount of wet food.
How much does a kitten eat?
Kittens have a very high energy requirement (about 2.5 times the resting requirement) and are fed several small portions or free-choice — ideally with dedicated kitten food.
My cat is gaining weight — what should I do?
Calculate the amount for the target weight and reduce slowly. Important: treats count in full and should make up at most 10% of daily calories. Check the figure (ribs easy to feel, slight waist) rather than only the scale.
Do treats count towards the food amount?
Yes, absolutely. They should make up at most 10% of daily calories; shorten the main meal accordingly, otherwise weight gain looms.
How often should I feed my cat?
At least two meals, ideally several small portions across the day — cats are snackers by nature. Kittens need three to four meals. Always provide fresh water.
More tools
Based on: Energy requirement via RER (70 × kg^0.75) and MER factor per life situation; energy density of the food as declared on the packaging. Results are guideline values and never replace a visit to the vet on health questions.