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Cat Calorie Calculator
Use this free cat calorie calculator to find how many calories your cat needs each day. Enter your cat's weight, life stage, and activity level, and it works out the resting energy requirement (RER = 70 × weight in kg^0.75), the daily calorie need, and how many cups of food that means at your food's kcal per cup.
Check the kcal per cup on your cat food bag — it is usually printed near the feeding guide. If your food lists kcal per kg instead, divide by the cups per kg on the bag.
Resting vs daily calories
RER is what your cat burns at rest. Daily calories (MER) add the extra energy for growth, activity, and body condition on top of it.
How it works
Figuring out how much to feed a cat is harder than it looks, because the number on the food bag is a rough guide for an average cat — and very few cats are average. This cat calorie calculator works out your own cat's daily calorie needs from its weight and life stage, then turns those calories into cups of food, so you can measure meals instead of guessing.
The calculation starts with the resting energy requirement, or RER. That is the energy a cat burns in a day just staying alive — breathing, keeping warm, running its organs — while resting in a comfortable room. Vets calculate it with a formula based on body weight in kilograms, raised to the power of 0.75. The 0.75 power matters: a cat that weighs twice as much does not need twice the calories, because larger bodies are more efficient per pound. That is why a 20-pound cat needs far less than double the food of a 10-pound cat, and why feeding by simple proportion overfeeds big cats.
If your cat's weight is in pounds, the calculator converts it first: one pound is 0.4536 kg, so a 10-pound cat weighs about 4.54 kg. Raising 4.54 to the power of 0.75 gives about 3.11, and 70 × 3.11 gives an RER of about 218 calories a day. That is the resting number, before any allowance for moving, playing, growing, or staying warm.
The second step multiplies the RER by a factor for life stage and condition, giving the maintenance energy requirement, or MER — the calories your cat actually needs each day. A neutered adult cat uses a factor of 1.2, because neutering lowers energy needs slightly. An intact adult uses 1.4. Kittens need much more for their size: 2.5 under four months old and 2.0 from four to twelve months, because they are building new tissue every day. Seniors use about 1.1, and a cat that is overweight or barely moves uses 1.0.
The last step is the practical one: turning calories into food. Every cat food lists its energy density, usually as kilocalories per cup, printed near the feeding guide on the bag. Divide the daily calories by that number and you get cups per day. At 400 kcal per cup, a cat needing 261 calories a day gets about 0.65 cups — roughly two-thirds of a cup — split across its meals. If you feed twice a day, that is about one-third of a cup per meal. The calculator's default of 400 kcal per cup is only a starting point; always check your own bag.
Weigh your cat every few weeks while you settle on a portion, and adjust by about 10% at a time. You should be able to feel the ribs easily under a thin layer of fat without pressing hard, and see a waist from above and a slight tuck from the side. If the ribs are hard to find, cut the portion a little; if the hip bones stick out, add a little.
Worked example
Take a healthy adult cat that has been neutered, weighs 10 pounds, lives indoors with normal activity, and eats a dry food with 400 kcal per cup. Here is exactly what the calculator does.
Step 1 — Convert the weight. 10 lb × 0.4536 = 4.54 kg.
Step 2 — RER. Raise 4.54 to the power of 0.75, which gives 3.11, then multiply by 70: 70 × 3.11 = 218 calories per day at rest.
Step 3 — MER. A neutered adult uses a factor of 1.2, and normal indoor activity uses 1.0, so 218 × 1.2 × 1.0 = 261 calories per day.
Step 4 — Cups of food. 261 ÷ 400 kcal per cup = 0.65 cups a day, or about two-thirds of a cup.
Step 5 — Per meal. Fed twice a day, that is 0.65 ÷ 2 = 0.33 cups per meal, about one-third of a cup each morning and evening. Enter the same numbers — 10 lb, adult neutered, normal activity, 400 kcal per cup, 2 meals — and the tool shows exactly these results, with the chart comparing the 218-calorie resting figure against the 261-calorie daily need.
FAQ
How many calories does a cat need per day?
A typical 10-pound neutered adult cat needs about 260 calories a day, but the range is wide: a kitten can need over 400, while a quiet senior may need under 200. Weight, age, neutering, and activity all shift the number, which is why this calculator asks for life stage instead of using one flat figure for every cat.
Should I feed my cat by the guide on the food bag?
Use the bag as a starting point, then adjust for your cat. Bag guides are written for an average cat and often run high, because pet food companies would rather a cat eat slightly too much than too little. Weigh your cat every few weeks and change the portion by 10% if its weight drifts the wrong way.
How much wet food equals a cup of dry food?
Wet food is mostly water, so the comparison is by calories, not volume. A typical 3-ounce can holds about 70 to 100 calories, while a cup of dry food holds about 350 to 450. A cat needing 260 calories a day would need about three cans of wet food, or a mix — for example one can plus a third of a cup of dry food.
Is it okay to leave dry food out all day?
Free feeding works for some cats, especially active kittens, but it is the most common cause of overweight indoor cats. Measured meals give you control: you know exactly how much went in, you notice sooner when appetite drops, and you can split food across two or three meals, which suits a cat's natural habit of eating small amounts often.
How do I know if my cat is overweight?
Feel the ribs: you should find them easily under a thin fat layer without pressing hard. Look from above for a visible waist behind the ribs, and from the side for a slight upward tuck at the belly. If the ribs are hard to feel or there is no waist at all, your cat is likely overweight and the portion should come down by about 10%.