How Much Should I Feed My Cat per Day? (grams calculator)

It depends on body weight and life stage. A 4 kg neutered indoor adult needs about 68 g/day of standard kibble (~350 kcal/100g). The formula: RER = 70 × (4^0.75) ≈ 198 kcal; MER = 198 × 1.2 ≈ 238 kcal; divide by 3.5 kcal/g = ~68 g/day. A 5 kg cat needs ~80 g/day; a 3 kg cat needs ~56 g/day. Always verify the kcal density on your specific food label and adjust proportionally.

Wet food contains ~70–80% water and delivers only 80–120 kcal per 100g, compared to 300–400 kcal per 100g for dry kibble. A 4 kg neutered adult needing 238 kcal/day requires roughly 264 g of average wet food (90 kcal/100g). That is about 3–4× more grams than dry food for the same caloric intake. Split across 2 meals daily for best digestion.

RER stands for Resting Energy Requirement — the calories a cat burns at complete rest (breathing, heartbeat, organ function). It's calculated as 70 × weight_kg^0.75 kcal/day, based on metabolic scaling established by the NRC and adopted by WSAVA/AAHA. All life-stage adjustments multiply from this baseline, so an accurate RER is the most critical step in any feeding calculation.

Yes — neutered and spayed cats have a MER factor of approximately 1.2× RER, compared to 1.4–1.6× for intact adults of the same weight. That is roughly a 20–25% reduction in daily calories. Not adjusting food quantity after surgery is one of the leading causes of feline obesity, which affects an estimated 30–35% of pet cats in North America.

Always use the ideal weight. If a cat weighs 7 kg but should weigh 5 kg, calculating RER on 7 kg will overshoot by ~30%. Use the target ideal weight and, for weight loss, apply a MER factor of 0.8× RER. Safe weight loss in cats is 0.5–2% of body weight per week; faster loss risks hepatic lipidosis (fatty liver disease).

Kittens under 1 year use a MER factor of 2.5× RER — more than double a neutered adult. A 2 kg kitten: RER ≈ 118 kcal/day, MER ≈ 294 kcal/day → ~84 g of dry food or ~327 g of wet food per day. Divide into 3–4 smaller meals because kittens have smaller stomachs and higher metabolic rates than adults.

They are a starting point, not a precise prescription. Manufacturer guidelines are typically formulated for intact, moderately active cats and are often set slightly high. Studies comparing bag guidelines to NRC-calculated MER show discrepancies of 15–30% in many cases. Cross-check with the RER/MER formula using your cat's actual weight and life stage, then adjust based on body condition score every 2–4 weeks.

Calculate the total daily calorie target (MER). Decide what percentage will come from each food type — e.g., 50% dry and 50% wet. For a 4 kg neutered cat with MER = 238 kcal: 50% = 119 kcal from dry (119 ÷ 3.5 = 34 g) + 50% = 119 kcal from wet (119 ÷ 0.9 = 132 g). Add up the two gram portions. Avoid estimating by volume — always weigh with a kitchen scale.

It depends on the senior stage. Cats aged 7–11 years (mature adult) often become less active and may need 10–15% fewer calories (MER ≈ 1.1× RER). However, cats over 11 years old frequently experience reduced nutrient absorption and muscle loss (sarcopenia), sometimes needing more protein and slightly more total calories. The NRC 2006 guidelines recommend individual assessment for seniors rather than a universal reduction.

Look for the Metabolizable Energy (ME) value on the label, usually stated as 'kcal/kg'. Convert: kcal/g = stated kcal/kg ÷ 1000. If not listed, estimate using modified Atwater factors from the Guaranteed Analysis: protein = 3.5 kcal/g, fat = 8.5 kcal/g, carbohydrate = 3.5 kcal/g. As a fallback, use 350 kcal/100g for dry kibble and 90 kcal/100g for wet food — both are safe market averages.