Cat Food Calculator: Daily Calories by Weight

How Cat Metabolism Differs From Dogs

Before running the numbers, it helps to understand why cats need their own calculation — not a scaled-down version of the dog formula.

Cats are obligate carnivores. Unlike dogs, cats have a very limited ability to metabolise plant-based carbohydrates. Their metabolism is built around protein and fat as primary fuel sources. High-carbohydrate dry food is metabolically problematic for many cats in a way it isn't for dogs.

Cats have a lower thirst drive. Cats evolved in arid environments and historically derived most of their water from prey. Dry food provides 10% moisture; wet food provides 75–80%. Cats fed exclusively dry food are in a chronic state of mild dehydration, which contributes to urinary tract disease and kidney disease.

Cats are more sensitive to overfeeding. A 5 lb cat gaining half a pound has gained 10% of their body weight. The health consequences — hepatic lipidosis, diabetes, joint disease — are severe and develop faster than in dogs.

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The RER Formula for Cats

RER (kcal/day) = 70 × (body weight in kg)^0.75

Worked example — 4 kg (8.8 lb) adult indoor spayed cat:

• 4^0.75 = approximately 2.83
• 2.83 × 70 = 198 kcal/day RER
• Multiply by neutered indoor adult multiplier (1.2): 198 × 1.2 = 238 kcal/day

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Life Stage Multipliers for Cats

Important: Geriatric cats (15+) often lose weight rather than gain it due to reduced digestive efficiency and muscle loss. Very old cats may need MORE calories, not fewer — the opposite of the pattern seen in senior dogs.

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Daily Calorie Requirements by Weight

An overweight 14 lb cat whose ideal weight is 10 lbs should be fed based on the 10 lb target, not 14 lbs.

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Converting Calories to Food Amounts

Formula: Daily amount = Daily kcal target ÷ Food's kcal per cup (or per gram, or per can)

Dry food (typically 300–500 kcal/cup): Example: 10 lb cat, 259 kcal target, food at 350 kcal/cup → 259 ÷ 350 = ¾ cup per day

Wet/canned food (3 oz can = 70–100 kcal, 5.5 oz can = 130–200 kcal): Example: 10 lb cat, 259 kcal target, 5.5 oz can at 180 kcal → 259 ÷ 180 = 1.44 cans per day

Mixed feeding:

• Half a 5.5 oz can: 90 kcal
• Remaining budget: 259 − 90 = 169 kcal
• At 350 kcal/cup dry: 169 ÷ 350 = 0.48 cups dry food

Use our Cat Food Calculator to get the exact daily amount for your cat's specific weight, age, food type, and caloric density.

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The Problem With Free Feeding

Free feeding — leaving dry food available at all times — is the most common feeding method for cats and the most significant driver of feline obesity. Studies show indoor cats fed ad libitum consume 20–30% more calories than cats on measured meal feeding.

Never free feed: overweight cats, multi-cat households, cats with diabetes, kidney disease, or urinary conditions.

May tolerate free feeding: thin or underweight cats, kittens under 6 months, cats with hyperthyroidism or conditions causing weight loss.

For most adult indoor cats, two measured meals per day is the optimal approach. It allows precise caloric control and lets you monitor appetite changes — an early indicator of illness in cats.

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Ideal Body Condition Score for Cats

• 1–3: Underweight. Ribs, spine, and hip bones clearly visible.
• 4–5: Ideal. Ribs palpable with slight fat cover. Visible waist from above. Slight abdominal tuck.
• 6–7: Overweight. Ribs difficult to feel. No visible waist. Rounded abdomen.
• 8–9: Obese. Heavy fat deposits. No waist. Fat pads at base of tail and thorax.

Feel your cat's ribs. You should feel them with gentle pressure, similar to the feeling of knuckles on a relaxed fist. If you cannot feel ribs without firm pressure, your cat is overweight.

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Weight Loss in Cats: Special Cautions

Cats cannot be put on aggressive caloric restriction. Rapid weight loss triggers hepatic lipidosis (fatty liver disease) — a potentially fatal condition where the liver becomes overwhelmed by fat mobilisation.

• Safe weight loss rate: No more than 0.5–1% of body weight per week
• Never reduce below 80% of RER — for a 14 lb cat, do not feed below 220 kcal/day
• If your cat needs to lose more than 15% of current body weight, involve your vet

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Kitten Feeding: High Demand, Short Window

Transition to adult feeding gradually between 10–12 months. Feed kitten-specific food until 12 months — adult formulas do not provide adequate protein, DHA, and calcium for development.

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Senior and Geriatric Cat Nutrition

Senior cats (7–11 years) generally need slightly fewer calories — multiplier 1.1–1.2. Geriatric cats (11+) are more complex. Many lose weight due to reduced digestive efficiency, dental pain, hyperthyroidism, or kidney disease.

A geriatric cat losing weight is not normal ageing — it is a clinical sign requiring investigation. Use our Pet Age Calculator to track your cat's life stage. Regular senior vet checks should include thyroid and kidney panels — budget with our Vet Cost Estimator.

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Reading a Cat Food Label

Caloric Content Statement (required by AAFCO since 2013): Shows kcal per kg AND kcal per cup or can. Example: "Caloric content: 3,500 kcal/kg, 350 kcal/cup." This is what you need for portioning.

Feeding Guide on the packaging: Use as a rough cross-check only — almost always an overestimate designed to sell more product.

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Dangerous Foods for Cats

Before giving your cat any human food, use our Food Safety Checker. Key toxins:

• Onions and garlic (all alliums): Cause haemolytic anaemia. Even garlic powder in cooked food counts.
• Raw fish fed exclusively: Creates thiamine deficiency over time.
• Dog food as a staple: Lacks taurine, arachidonic acid, and vitamin A at feline requirements. Causes blindness and heart disease.
• Xylitol: Extremely toxic. Check all peanut butter and sugar-free products.
• Grapes and raisins: Cause acute kidney failure.
• Alcohol and caffeine: Both toxic in very small quantities relative to cat body weight.

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Recommended Tools

• Cat Food Calculator — Exact daily portions in grams and cups for wet, dry, or mixed feeding.
• Pet Age Calculator — Track your cat's life stage. Senior and geriatric cats have different caloric dynamics.
• Dog Food Calculator — Use separate calculators for dogs and cats. Dog food does not meet feline requirements.
• Food Safety Checker — Check any human food before giving to your cat.
• Vet Cost Estimator — Budget for twice-yearly senior vet visits including thyroid and kidney panels.
• Pet Insurance Calculator — Kidney disease, hyperthyroidism, and diabetes are common in older cats and expensive long-term.
• Adoption Cost Calculator — Full first-year cost breakdown for a new cat.
• Raw Dog Food Calculator — The percentage-of-body-weight methodology applies to raw cat feeding with feline-specific ratios.

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Calculate Your Cat's Exact Daily Portions

→ Use the Cat Food Calculator to get your cat's personalised daily portion in grams and cups — for wet food, dry food, or a combination — in under 60 seconds.