⚖️ Cat Calorie & Feeding Calculator
The feeding guide on the bag is written for an average cat who doesn't exist. This one uses yours: weight, life stage, activity and goal go in — daily calories, exact grams, cups, cans and a water target come out.
Your cat
No scale? Weigh yourself holding the cat, then without, and subtract. Vet visits give the most honest number.
Not sure of the ideal? Your vet's last "perfect weight" note, or our BCS guide, will pin it down.
1 = ribs and spine sharp · 5 = ribs felt under a light fat cover, waist visible · 9 = no waist, heavy deposits. Used only for a sanity-check note.
Your food
On the bag as kcal/kg ÷ 10, or "metabolisable energy". Typical dry: 350–420.
On the tin/pouch label. Typical wet: 70–100.
Daily target
That is, in real food
💧 Daily water target
Figures update as you type — no Calculate button to hunt for. Weigh monthly and adjust by ±10% if the trend isn't matching the goal.
Why use this calculator?
The bag's guide isn't written for your cat
Packet feeding charts assume an "average" — often intact, active — cat, and studies keep finding they overfeed typical neutered indoor cats. Your cat's number comes from their weight, stage and goal, using the same RER/MER formulas vets use.
Grams end the cup lottery
A "cup" of kibble varies wildly by who scoops and how it settles — easily ±25% a day. Converting your calories into weighed grams (and exact cans) removes the single biggest source of accidental overfeeding.
The treats budget makes the invisible visible
Treats commonly sneak in 20–30% extra calories. Reserving the standard 10% up front — and printing it as a number — turns "just one more" into a decision you can actually see.
How the numbers work
| Step | Formula | Notes |
|---|---|---|
| Resting energy (RER) | 70 × (weight in kg)0.75 | The baseline every vet-nutrition calculation starts from (Merck Veterinary Manual) |
| Daily energy (DER) | RER × life-stage factor | Kitten ×2.0 · neutered adult ×1.2 · intact ×1.4 · senior ×1.1 · weight loss ×1.0 of ideal weight · weight gain ×1.3 of ideal |
| Activity adjustment | ±10% | Relaxed indoor ×0.95 · average ×1.0 · very active ×1.1 — fine-tuning, not gospel |
| Portions | food kcal ÷ your food's kcal/100 g | That's why your bag's real energy number matters — check the label, not our defaults |
| Water | ~50 ml per kg per day | Wet food (~75% water) covers most of it; dry food (~10%) barely dents it |
Guidance follows the Merck Veterinary Manual and AAHA/WSAVA nutrition guidance, reviewed November 2026. Individual cats vary — the monthly weigh-in trend outranks any formula, including this one.
Not covered here, on purpose
Pregnant and nursing queens, cats with kidney, diabetic, thyroid or other diagnosed conditions, and kittens under 8 weeks need feeding plans built with a vet — their numbers genuinely differ, and a general calculator would be guessing with your cat's health.
Questions people ask
Why does the bag say to feed more than this?
Bag charts are built to cover the most energetic cats in the weight band, rounded up, often for intact animals — and no manufacturer was ever sued for a chubby cat. For a neutered indoor cat they're commonly 20–30% generous. Feed the cat in front of you: monthly weight trend is the referee.
My cat acts starving on the "right" amount. Are they?
Almost never — begging is a learned behaviour, and it works because it worked once. Hunger theatre peaks in week one of a new portion. Puzzle feeders, splitting the same calories into more, smaller meals, and play before dinner all help far more than extra food.
How fast should weight actually change?
Loss: about 0.5% of body weight per week is the safe, vet-standard pace — for a 6 kg cat that's ~30 g a week, ~120 g a month. Gain should be similarly gradual. Faster than that in either direction is a vet conversation, not a bigger portion swing.
Is free-feeding (food always out) OK?
For a slim, self-regulating cat it can be. For everyone else, measured meals win — you can't spot appetite changes (an early illness signal) in a cat whose bowl is always full, and multi-cat homes can't tell who's eating what.
Should senior cats eat less?
Slightly — the senior factor here (×1.1) reflects slower metabolism. But watch the trend: unintended weight loss in an older cat is a vet visit, not a success. Seniors also often do better on the same calories in more, smaller meals.
Keep exploring
Can Cats Eat…? Checker — what those treats can safely be · Cat Age Calculator — life stage drives the factor · Multi-Cat Resource Calculator — separate bowls, fewer food guards · All KittyButts tools
This calculator gives general feeding guidance for healthy cats, built on standard veterinary formulas — it is not veterinary advice and doesn't replace your vet's knowledge of your individual cat. Sudden appetite or weight change is always worth a vet visit. This is a feeding-amount tool, not a diagnosis tool.