Calculate daily calories and food portions for your adult cat based on WSAVA RER/MER formulas. Factor in spay/neuter status and activity level for precise feeding recommendations.
Most healthy cats between 1 and 6 years old thrive on a surprisingly simple rule: feed to maintain a lean body condition, not to a fixed cup count. The Adult Cat Feeding Calculator turns your cat's weight and lifestyle into a daily calorie target using the veterinary standard RER/MER method, then converts that target into dry, wet, and mixed-food portions you can actually measure.
Indoor adult cats are prone to gradual weight gain because they burn far fewer calories than their outdoor ancestors. A 10-pound indoor cat may need only about 180-200 kcal per day, while the same cat with outdoor access could need 15-25% more. Getting this number right is the difference between a healthy weight and the slow creep toward obesity that sets up diabetes and joint disease later.
The math starts with Resting Energy Requirement (RER) = 70 x (weight in kg)^0.75. This is the calories a cat needs at rest. For a 4.5 kg (10 lb) cat, RER is about 217 kcal. Maintenance Energy Requirement (MER) multiplies RER by a life-stage factor: 1.2 for a neutered adult, 1.4 for an intact adult, and about 1.0 if the cat needs to hold weight steady during a reduction plan.
AAFCO and WSAVA both treat 'adult maintenance' as the default nutrient profile for healthy adults. A complete and balanced commercial diet labeled for adult maintenance already contains the right protein, fat, vitamins, and minerals -- so the main job of feeding is portion control, not supplement juggling. Over-supplementing (especially calcium or fat-soluble vitamins) can unbalance the diet.
Protein quality matters more than a single percentage. Cats are obligate carnivores and need animal-source protein with a complete amino acid profile, including taurine, which they cannot synthesize. A diet meeting AAFCO standards will include taurine, but heavily home-prepared or unbalanced raw diets can fall short without careful formulation.
Open the Adult Cat Feeding calculator and enter your cat's weight in pounds. Pick neuter status (neutered or intact) and an activity level from sedentary indoor to very active outdoor. The tool returns a daily kcal target with the matching dry-cup and wet-can portions. Re-run it whenever the scale moves more than a pound.
Read the number as a starting point, not a rule. Weigh your cat every 2-4 weeks and nudge portions up or down by about 5-10% if body condition drifts. Keep a short log -- date, weight, cups/cans -- so trends show before they become problems.
The usual slip is trusting the feeding-guide range on the bag instead of your cat's actual RER. A 10 lb neutered cat needs about 260 kcal/day, yet many labels suggest 'up to 3/4 cup,' which can be 280+ kcal. Weigh the food and count treats -- one 15-kcal squeeze treat is roughly 6% of a small cat's whole day.
A second mistake is free-feeding dry food without monitoring intake, which makes overfeeding effortless for easy-keeper cats. A third is assuming 'grain-free' or 'premium' means more calories are fine -- calorie math, not marketing, sets the portion.
Indoor versus outdoor is the biggest real-world lever. Indoor cats sleep more and patrol less, so they usually land at the 1.2 factor; free-roaming cats burn more and need the higher end. Activity level, not just weight, should drive the number -- a slender but highly active cat can eat more than a couch-potato of the same size.
If your adult cat is at an ideal body condition (you can feel ribs but not see them, with a visible waist), the calculator's target is a maintenance number. If the cat is already overweight, switch to the weight loss calculator rather than just cutting this one's portions blindly.
Adult maintenance assumes a healthy cat at lean body condition. 'Adult' here means roughly 1-7 years; kittens, seniors, pregnant or nursing, and overweight cats use different factors, which is why we built a separate tool for each.
RER = 70 x (weight_kg)^0.75. For a 10 lb (4.54 kg) cat: 70 x 4.54^0.75 ≈ 217 kcal RER. Neutered MER = 217 x 1.2 ≈ 260 kcal; intact MER = 217 x 1.4 ≈ 304 kcal. The activity multiplier (0.9 sedentary, 1.0 standard, 1.1 active, 1.2 very active) trims or adds around that baseline.
Worked example: a 10 lb (4.5 kg) neutered indoor cat. RER = 70 x 4.5^0.75 = about 217 kcal. MER = 217 x 1.2 = about 260 kcal/day. If your dry food is 380 kcal/cup, that is 0.49 cup per day, best split into two 0.25-cup meals. Prefer wet? A 5.5 oz can at 180 kcal covers about 0.96 cans/day -- feed one can and trim the dry, or split one can across two meals with a small dry top-up. For a 50/50 mix, give 94 kcal from wet (about half a can) and 94 kcal from dry (0.25 cup). Weigh monthly: if the waist rounds and ribs get hard to feel, drop to about 170 kcal (0.45 cup); if the cat looks too lean, nudge up 5-10%. The number is a starting point -- body condition confirms it. Recalculate the target any time the cat gains or loses more than half a pound, is spayed or neutered, or changes from indoor-only to outdoor access. A simple body-condition check at home every two weeks -- ribs easy to feel with light pressure, visible waist from above, and a tuck behind the ribs -- keeps the calculator honest without a scale.
A common myth is that cats self-regulate and can free-feed safely; most indoor cats eat out of boredom and gain. Another is that 'grain-free' automatically means healthier -- what matters is the AAFCO statement and total nutrient balance, not the absence of grain. A third myth is that because cats are carnivores, more meat automatically means more food; protein aids satiety and lean mass, but total calories still govern weight, so portioning remains essential.
For adult cats the quiet risk is slow drift: a neutered indoor cat gaining 1-2 lb a year is the most common pattern. Sudden appetite loss, repeated vomiting, or weight change with normal eating warrants a vet visit -- hyperthyroidism, diabetes, and kidney disease all show up as eating or weight shifts.
Enter your cat's weight, spay/neuter status, and activity level to calculate daily calorie needs and food portions.
A 10-pound (4.5 kg) neutered adult cat needs approximately 260 kcal per day. This is calculated as: RER = 70 × (4.5)^0.75 ≈ 217 kcal, multiplied by the neutered factor of 1.2 = 260 kcal. The neutered factor of 1.2 already reflects normal activity, giving ~260 kcal/day. Adjust up for very active cats or down for sedentary indoor cats.
For a cat needing 200 kcal/day, that equals approximately 0.57 cups of dry kibble (assuming 350 kcal/cup). Always use a standard 8-ounce measuring cup, not a scoop or mug. Split the daily portion into 2-3 meals. Free-feed only if your cat self-regulates; most neutered cats will overeat if food is constantly available.
Spaying and neutering reduces circulating sex hormones (estrogen, testosterone) which decreases basal metabolic rate by 20-30%. This evolutionary adaptation prevents overconsumption when the cat is no longer investing energy in mating behaviors and reproduction. A neutered cat eating the same amount as before surgery will gradually gain weight. Switch to a "neutered" or "weight management" formula after surgery, or simply reduce portion sizes by 20%.
Both formats can provide complete nutrition if AAFCO-compliant. Wet food has advantages: higher moisture content (helping prevent kidney disease and urinary issues), higher protein density, and fewer carbohydrates. Dry food is more convenient, affordable, and can help mechanically clean teeth (though dental-specific diets are more effective). A mixed feeding approach — wet food for morning and evening meals, dry food for midday — combines the benefits of both. Use our calculator to determine portion sizes for either format.