Our calculator uses the veterinary RER formula to give your cat accurate daily calorie and portion recommendations. Cats are obligate carnivores, their needs differ significantly from dogs.
RER × Life-stage multiplier · WSAVA standards
🩺 General estimates based on WSAVA nutritional guidelines. Consult your veterinarian before significant diet changes.
Cats are obligate carnivores, unlike dogs, they cannot synthesize certain essential nutrients (like taurine, arachidonic acid, and vitamin A) from plant sources. This means cats must get these nutrients directly from animal tissue. This is why "all life stages" dog food is never suitable for cats, and why a proper cat-specific diet is essential.
The RER formula works the same for cats as dogs (70 × weight^0.75), but the multipliers are adjusted for feline metabolism. Indoor cats especially tend to be sedentary, which means they need fewer calories than many owners expect. Obesity is a leading health problem in domestic cats, a 5 kg cat that should weigh 4 kg is technically 25% overweight.
Hydration is another critical factor for cats. Cats evolved in arid environments and have a naturally low thirst drive. Wet food (which is 70-80% water) can significantly improve hydration and reduce kidney disease risk, especially in senior cats. Check out our Water Intake Calculator and Cat Nutrition Guide for more detail.
Our feeding calculator uses metabolic energy requirement (MER) formulas endorsed by the World Small Animal Veterinary Association (WSAVA) and the National Research Council (NRC) to determine your cat's daily calorie needs.
An average 4 kg indoor adult cat needs roughly 200-250 kcal per day, equivalent to about 55-70g of dry food or 200-250g of wet food. Use our calculator for your specific cat, then check your brand's calorie content. Most commercial cat foods list kcal per 100g on the label.
Both can be nutritionally complete if they meet AAFCO or FEDIAF standards. Wet food provides more moisture, which is beneficial for urinary tract health and kidney function. Dry food is more calorie-dense and convenient. Many vets recommend a combination of both. Avoid feeding only dry food to cats prone to urinary issues.
Cats may act hungry even when well-fed due to habit, boredom, or the palatability of their food rather than true hunger. If your cat's weight and body condition are healthy, resist overfeeding. Some cats do better with multiple small meals (3-4x/day) using a timed feeder. Rule out medical causes like hyperthyroidism or diabetes with a vet visit.
Most veterinary nutritionists recommend a combination of wet and dry food. Wet food provides essential hydration, which supports kidney health and helps prevent urinary tract issues. Dry food offers dental benefits through mechanical abrasion and is more calorie-dense, making portion control easier. The ideal ratio depends on your cat's health status, age, and hydration habits.
Change food quantities gradually over 7 to 10 days. Start by adjusting portions by no more than 10 percent every two days. Sudden calorie changes can cause digestive upset or food refusal in cats. Monitor your cat's weight weekly during transitions and adjust based on body condition rather than strictly following a calculator output.