Feeding your cat the right daily amount is one of the most important things you can do for their long-term health. Too little food causes nutritional deficiencies, while overfeeding leads to obesity, diabetes, and joint problems in cats. This calculator uses the standard veterinary energy model to estimate your cat's daily needs. The calculation starts with RER (Resting Energy Requirement): RER = 70 x bodyweight^0.75 kcal/day. This is multiplied by a lifestyle factor to give MER (Maintenance Energy Requirement): neutered/spayed 1.2; low-activity 1.4; active 1.6; kitten/pregnant 2.0. Results are a starting point — always consult your vet.
The calculator uses the standard energy model employed by veterinary nutritionists worldwide. **Step 1 — RER (Resting Energy Requirement):** RER = 70 x bodyweight^0.75 kcal/day. The formula accounts for the non-linear relationship between metabolism and body mass — larger cats require proportionally fewer calories per kilogram than smaller cats. **Step 2 — MER (Maintenance Energy Requirement):** Actual daily needs depend on lifestyle. We multiply RER by the appropriate factor: neutered/spayed 1.2 (reduced metabolism post-surgery); low-activity 1.4; active 1.6; kitten (under 1 year) 2.0 (rapid growth); pregnant/nursing 2.0 (elevated needs). **Step 3 — converting to grams:** MER is divided by the food's caloric density (kcal/100g) and multiplied by 100 to get grams. For wet food, the calculator also returns the number of standard 85 g pouches needed. Note that these are population-average formulas. An individual cat may need +/-20% depending on breed, individual metabolism, and health status.
Step 1 — RER: 70 x 4^0.75 = 70 x 2.83 ≈ 198 kcal/day. Step 2 — MER: 198 x 1.2 (neutered factor) ≈ 238 kcal/day. Step 3 — dry food: 238 / (350/100) ≈ 68 g/day. In practice, a 4 kg neutered cat needs about 68 g of dry food split into 2-3 meals per day. For wet food (80 kcal/100g): 238 / 0.8 ≈ 298 g, which is approximately 3.5 standard 85 g pouches per day.
A 4 kg neutered adult cat has an MER of approximately 238 kcal/day. For dry food at 350 kcal/100g that works out to about 68 g per day. For wet food (80 kcal/100g), you need around 298 g or about 3.5 standard 85 g pouches. Verify with the feeding guide on your specific food packaging.
RER (Resting Energy Requirement) is the energy a cat needs to sustain basic life functions at rest — the feline equivalent of the human BMR. It is calculated as: RER = 70 x bodyweight_kg^0.75 kcal/day. For a 4 kg cat, RER ≈ 198 kcal/day. The exponent 0.75 means larger cats need proportionally fewer calories per kilogram than smaller cats.
RER is the resting baseline, while MER (Maintenance Energy Requirement) is the total daily caloric need after accounting for lifestyle. MER = RER x lifestyle factor. For a neutered cat the factor is 1.2, for an active cat 1.6, and for kittens or pregnant cats 2.0. MER is what you actually feed.
Kittens under 1 year old have a much higher energy demand due to rapid growth — the MER factor is 2.0, meaning they need nearly twice as many calories as a neutered adult of the same weight. Divide the daily amount into 3-4 small meals until 6 months old. Always use a kitten-specific formula food with higher protein and caloric density.
Both can be excellent choices. Wet food contains 75-80% moisture, which naturally supports hydration — important because cats have a low thirst drive. Dry kibble is calorie-dense, easy to store, and convenient. Many vets recommend mixing both types for optimal nutritional balance. If mixing, adjust portions according to each food's calorie contribution.
The calculator automatically converts daily wet food grams into the number of standard 85 g pouches. For example, if your cat needs 298 g of wet food per day, that equals about 3.5 pouches (298 / 85 ≈ 3.5). Check your specific product — pouch sizes may vary between brands (usually 70-100 g).
Neutering or spaying reduces a cat's resting metabolic rate by approximately 20-30%. The MER factor drops to 1.2. It is important to reduce daily portions after the procedure and monitor body weight closely. Neutered cats are significantly more prone to weight gain and obesity if fed the same amount as before surgery.
Pregnant and nursing cats have an MER factor of 2.0 — the same as kittens. A 4 kg pregnant cat needs approximately 396 kcal/day and about 113 g of dry food (350 kcal/100g). Many vets recommend feeding kitten food during pregnancy and nursing due to its higher caloric and protein density. Always consult your vet for pregnant cats.
Adult cats are typically fed 2-3 times per day. Kittens under 6 months need 3-4 meals daily due to their small stomach capacity. Older or ill cats may have a specific feeding schedule recommended by a vet. The total daily amount stays the same regardless of how many meals you split it into.
No. The calculator provides a scientifically-grounded estimate using standard veterinary energy formulas based on AAFCO guidelines. However, individual cats vary — breed, body condition score, health status, and specific food composition all affect real needs. Always consult a vet or certified veterinary nutritionist for cats with chronic illness or unusual dietary requirements.
Indicative portion only — consult your veterinarian. Calculator results are based on standard energy formulas and do not replace individual dietary or veterinary advice. For cats with chronic illness, obesity, or special dietary needs, always seek professional veterinary guidance.
Calculate how many calories your dog needs per day. The RER and MER calculator accounts for weight, age, activity level and physiological status (pregnancy, nursing, obesity). Also shows dry and wet food amounts.
Calculate how much food your dog needs per day. Enter weight, life stage and food calorie density — get RER, MER and grams of dry or wet food. Free, no signup required.