Cat Calorie Calculator · Daily Calories & Feeding Guide

Cat Calorie Calculator

Find how many calories your cat needs per day based on weight, age and activity

Setup
Calorie needs are based on RER (Resting Energy Requirement) = 70 × weight(kg)0.75, multiplied by a life-stage factor. Different cats need very different amounts.
Your cat
kg
lb
kg
Typical adult cat weight: 3.5–5.5 kg (8–12 lb). If your cat is overweight, use their ideal weight for calorie calculations — not their current weight.
Daily Calorie Needs
🐱 Adult maintenance
Daily calories (DER)
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—
RER (resting) — Activity factor —
RER (resting)
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Life-stage factor
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Daily calories (DER)
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Calories per meal (×2)
—
Current weight
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Ideal weight
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Weight to lose
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Weight to gain
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Calorie needs by life stage
Life stageFactorDaily calories for this catNotes
Daily calories by body weight (adult maintenance)
Weight (kg)Weight (lb)RER (kcal)Indoor (×1.2)Active (×1.4)Weight loss (×0.8)
Important notes
These are starting estimates, not prescriptions. Every cat is different — adjust based on body condition score, weight trend, and energy level. Weigh your cat every 2–4 weeks and adjust by 10% up or down as needed.
Never start a weight-loss diet without veterinary supervision. Cats losing weight too quickly can develop hepatic lipidosis (fatty liver disease), which is life-threatening. Safe weight loss is 1–2% of body weight per week.
Special cases: pregnant, nursing, growing kittens, and cats with medical conditions (kidney disease, diabetes, thyroid disease, cancer) have different calorie needs. Always consult your veterinarian for these cats.
Formula: RER = 70 × (weight kg)0.75 · DER = RER × life-stage factor. These are standard veterinary formulas used worldwide.
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Faiq Ur Rahman

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Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.

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Cat Calorie Calculator: How Many Calories Does Your Cat Need Per Day?

Enter your cat’s weight, life stage, and neuter status. The calculator returns a resting energy requirement, a daily calorie target, and a per-meal portion. It also factors in an ideal weight for overweight cats, so the math runs on the weight your cat should be, not the weight they are. Use it to plan meals, track portions, or prepare questions for your vet.

Most cat owners guess at portions. A scoop here, half a can there, and no idea whether the total lands anywhere near what the cat actually burns. Meanwhile the cat gets heavier by a few hundred grams a year, and nobody notices until the vet says something. This calculator removes the guessing. It uses two standard veterinary formulas, RER and DER, to turn a weight and a life stage into a real calorie number. Kittens, seniors, nursing mothers, and overweight cats all get their own factor, because a growing kitten needs more than twice what a sedentary adult does. The result is a starting point you can adjust as you watch your cat’s weight.

 

How to Use the Cat Calorie Calculator

  1. Pick your weight unit at the top: kilograms or pounds.

  2. Select the life stage and status that matches your cat. The dropdown is grouped into kitten, adult, senior, and special categories.

  3. Type your cat’s current weight into the first field.

  4. Set an ideal or target weight. If your cat is at a healthy weight, this is the same number.

  5. Choose a body condition score from thin through to obese.

  6. Read the daily calorie target in the large result panel.

  7. Check the per-meal figure, which splits the daily total based on the feeding frequency for that life stage.

  8. Adjust the life stage if the result looks off, and watch the target update live.

 

How the Cat Calorie Calculator Formula Works

The calculator runs two formulas back to back. RER gives you the calories a cat burns doing nothing at all. DER multiplies that by a life-stage factor to reflect real daily activity and growth.

Formula: RER = 70 × (body weight in kg)^0.75
Formula: DER = RER × life-stage factor

The exponent 0.75 matters. It’s why a cat twice the weight of another doesn’t need twice the calories. A 4 kg cat and an 8 kg cat differ by roughly 68% in RER, not 100%. Weight is converted to kilograms first if you’re working in pounds, using 0.45359237 kg per pound.

The life-stage factor is where the calculator does its real work. Here’s the full set:

Life stageFactorWhat it reflects
Kitten under 4 months×2.5Rapid growth
Kitten 4–9 months×2.0Steady growth
Kitten 9–12 months×1.8Approaching adult size
Intact adult×1.4Un-neutered, higher metabolism
Neutered adult, active×1.2Standard healthy indoor cat
Neutered adult, sedentary×1.0Low-activity indoor cat
Senior, 8+ years×1.1Slight metabolic change
Geriatric, 12+ years×1.1Older cat, frequent monitoring
Overweight, weight loss×0.8Vet-supervised reduction
Pregnant, last 4 weeks×1.8Late gestation
Nursing / lactating×2.5Milk production

One behaviour worth knowing: if you pick the overweight stage, the calculator switches to using the ideal weight rather than the current weight. That’s deliberate. Calorie targets for weight loss are set against the weight the cat should be, not the weight they’re carrying. Feeding a 6.5 kg cat at 6.5 kg RER just maintains the problem.

Per-meal calories are split by life stage: 4 meals for kittens under 4 months and nursing mothers, 3 meals for older kittens, and 2 meals for everyone else. If current weight, ideal weight, or both are blank or zero, the tool returns an invalid input message instead of a number.

 

Worked Example: A 5.2 kg Neutered Indoor Cat

Your cat weighs 5.2 kg. She’s spayed, indoor-only, and her vet says she’s carrying a bit extra. You set the ideal weight at 4.4 kg and pick the overweight stage.

  1. RER at ideal weight: 70 × 4.4^0.75 = 70 × 3.04 = about 213 kcal

  2. Weight-loss factor: × 0.8

  3. DER: 213 × 0.8 = about 170 kcal per day

Now compare the same cat on the neutered-adult-active stage at her current weight:

  1. RER at 5.2 kg: 70 × 5.2^0.75 = 70 × 3.44 = about 241 kcal

  2. Active factor: × 1.2

  3. DER: 241 × 1.2 = about 289 kcal per day

That’s a 119 kcal gap between maintaining her current weight and a supervised reduction. Split across two meals, the weight-loss plan is roughly 85 kcal per meal. Weigh it with a kitchen scale. A heaped quarter-cup of dry food can easily run 30% over a level one, which would wipe out the deficit in a single meal.

Frequently Asked Questions

How many calories should I feed my cat per day?

A typical 4.5 kg neutered indoor cat needs around 260 kcal a day. Feed that for two to three weeks, then adjust by 10% based on the scale and rib check. Kittens, nursing mothers, and overweight cats need very different numbers.

 

How do I calculate my cat’s RER?

Multiply 70 by your cat’s weight in kilograms raised to the power of 0.75. A 4 kg cat gives 70 × 2.83, or about 198 kcal. Most phone calculators handle the ^0.75 with a y^x button.

 

Can I put my cat on a diet without seeing a vet?

No. Cats losing weight fast can develop hepatic lipidosis, which is often fatal. Safe loss is 1–2% of body weight per week. Get your vet to confirm the target weight and calorie number before you cut portions.

 

How fast can a cat safely lose weight?

One to two percent of body weight per week. For a 5 kg cat that’s 50 to 100 grams. Any faster and the liver is at risk. A 1.5 kg reduction usually takes two to three months of consistent feeding.

 

Do indoor cats need fewer calories than outdoor cats?

Yes, roughly 20% fewer. Indoor cats move less and don’t burn energy staying warm. Use the sedentary setting if your cat sleeps most of the day, or the active setting if she plays hard and moves around the house all evening.

 

What is a good body condition score for a cat?

A 5 out of 9 is ideal. You should feel each rib under light pressure, see a waist tuck from above, and feel a small amount of belly fat. Scores of 6 and above mean the ribs are getting harder to feel.

 

Should I use my cat’s current weight or ideal weight for the calorie calculation?

Ideal weight, if your cat needs to lose weight. Feeding at the current weight keeps the cat at the current weight. The calculator switches to ideal weight automatically when you pick the overweight stage.

 

Does neutering change how many calories my cat needs?

Yes. Neutering drops energy needs by 20–30%. An intact adult runs at ×1.4, a neutered one at ×1.2 or lower. Appetite doesn’t drop with it, so portions usually need to be reduced after surgery.

 

How many meals a day should I feed my cat?

Two meals works for most adults. Kittens under four months need four smaller meals, older kittens need three, and nursing mothers should be fed four or more times. Total daily calories matter more than the split.

 

Why is my cat always begging for food?

Hunger often means the calorie split is off rather than the total. Cats fed one large meal get hungry again hours later. Try splitting the same daily calories into three or four smaller portions. If the begging is new, get a vet check first.

Disclaimer

This calculator gives a starting estimate, not a feeding prescription. Every cat is different, and a number that works for one may not suit another of the same weight. Use the result as a baseline, then adjust based on body condition and weight trend over two to four weeks. Never start a weight-loss diet without veterinary supervision, because cats losing weight too quickly can develop hepatic lipidosis. Cats with kidney disease, diabetes, thyroid disease, cancer, or any ongoing medical condition have different calorie needs. Pregnant, nursing, and growing cats also fall outside standard adult guidelines. Speak to your veterinarian before changing what or how much you feed.

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