Cat Calorie Calculator

This cat calorie calculator estimates how many calories your cat needs per day. It converts your cat’s body weight into its Resting Energy Requirement (RER), then multiplies RER by one published feline factor chosen from its life stage and profile, such as neutered or intact. You’ll see the RER, the exact factor used and the estimated daily calories. The result is a starting estimate to monitor and adjust, not a veterinary prescription.

Last updated: 26 September 2026 · Educational tool, not veterinary advice

Your cat’s details

Cat’s weight

Weight unit

Use current weight. If your cat is well over or under a healthy weight, ask your vet which weight to use.

Life stage

Kitten Adult Senior

Cat profile (choose one)

Neutered / spayed Typical adult cat that has been neutered or spayed Intact Not neutered or spayed Inactive or obesity-prone Mostly resting, or gains weight easily. Not a weight-loss plan.

Your cat’s calorie estimate

Enter your cat’s weight, life stage and profile, then press Calculate My Cat’s Calories. You’ll see RER, the factor used and estimated kcal/day.

How to Use the Cat Calorie Calculator

Enter your cat’s weight.
Choose kg or lb.
Select life stage: kitten, adult or senior.
Choose the one profile that fits (shown for adults and seniors).
Press Calculate.
Review the RER, the factor used and the estimated daily calories.
Need a food amount? Use the Cat Food Calculator to convert calories into a portion of your actual food.
Planning weight loss? Use the Cat Weight Loss Calculator for a target-weight-based starting calorie estimate instead.
Turning calories into food? See How Much Should I Feed My Cat to Lose Weight? for a worked example.

How the Cat Calorie Calculator Works

Weightconverted to kg
RERresting baseline
One feline factorfrom the table below
Estimated daily caloriesRER × factor

RER (Resting Energy Requirement) is roughly the energy a cat uses at rest. It’s a baseline, not the final daily target. Daily needs are estimated by multiplying RER by one factor that describes your cat. The calculator never stacks extra multipliers for activity, age or body condition on top.

Cat Calorie Calculator Formula

RER = 70 × (body weight in kg)^0.75

Estimated daily calories = RER × feline factor

Pounds are converted first (1 kg = 2.2046226218 lb). The 0.75 power means energy needs grow more slowly than body weight: a 6 kg cat’s RER is about 1.35 times a 4 kg cat’s, not 1.5 times. Pet Nutrition Alliance gives this same RER equation for cats and dogs.

Feline Energy Factors Used

These are the only factors the calculator uses. They match the Cat Food Calculator, so both tools give the same calorie estimate.

Profile	Factor	When used	Source basis	Important limitation
Neutered/spayed adult	1.2 × RER	Adult or senior + “Neutered / spayed”	Merck 1.2; Pet Nutrition Alliance 1.2	A population starting point; individual cats vary.
Intact adult	1.4 × RER	Adult or senior + “Intact”	Merck 1.4; Pet Nutrition Alliance 1.4	A population starting point; individual cats vary.
Inactive or obesity-prone adult	1.0 × RER	Adult or senior + “Inactive or obesity-prone”	Merck “obesity prone” 1; Pet Nutrition Alliance “overweight-prone/inactive” 1.0	Not a weight-loss prescription. Intentional weight loss needs a vet plan.
Growing kitten	2.5 × RER	Kitten	Merck 2.5 (kittens may alternatively be fed free choice); Pet Nutrition Alliance growth 2–3	Needs change as kittens grow; not for pregnant or nursing cats.
Senior cats	No separate factor	Uses the adult rows above	Neither source publishes a senior factor	Older cats vary widely; see a vet about unexplained changes.

Illustrative example only

Worked Example: Calories for a 4 kg Neutered Adult Cat

Weight: 4 kg
RER = 70 × 4^0.75 = 70 × 2.83 ≈ 198 kcal/day
Factor for a neutered/spayed adult = 1.2
Estimated daily calories = 198 × 1.2 ≈ 238 kcal/day

This doesn’t mean every 4 kg cat needs exactly 238 calories. It’s a starting estimate to check against your cat’s weight and body condition over time.

Turn 238 kcal into grams, cups, cans or pouches with the Cat Food Calculator →

Understanding Your Result

The number shown is a starting estimate from one published factor, not a fixed requirement. Pet Nutrition Alliance notes that individual animals can vary by as much as 50% from predicted values, so monitor your cat’s weight and body condition and recheck the estimate when weight, life stage, neuter status, activity or health changes.

The profile you choose sets the factor: 1.2 × RER for a neutered adult, 1.4 × RER for an intact adult, 1.0 × RER for an inactive or obesity-prone adult and 2.5 × RER for a growing kitten. No separate senior factor is used. The total includes any treats; the Cat Food Calculator can set aside a treat allowance when working out a portion.

Want the full explanation of why two cats of the same weight can need different calories, and how to monitor whether an estimate is working? Read our complete cat calorie guide.

What About Overweight or Obesity-Prone Cats?

Merck lists 1 × RER for “obesity prone” cats, and Pet Nutrition Alliance lists 1.0 × RER for “overweight-prone/inactive” cats. That’s what the calculator’s inactive or obesity-prone profile uses: a maintenance starting estimate for cats that gain weight easily.

This profile is not a therapeutic weight-loss prescription. Cats shouldn’t be put on severe calorie restriction. If your cat needs to lose weight, ask your vet for an individual plan.

Calories vs Food Portions: What’s the Difference?

Calories are the energy target: what this calculator estimates.
A food portion is the amount of a specific food that provides those calories.

Foods differ in calories per cup, 100 g, can or pouch, so 238 kcal doesn’t equal one universal amount of food. To turn your cat’s calories into a real portion, use the Cat Food Calculator with the calorie information on your cat’s food.

Cat Calorie Calculator FAQ

How does a cat calorie calculator work?

It converts weight to kilograms, calculates the Resting Energy Requirement, then multiplies it by one published feline factor chosen from your cat’s life stage and profile to give estimated daily calories.

How many calories does a 4 kg cat need?

A 4 kg cat has an RER of about 198 kcal/day. For a neutered adult (1.2 × RER) the starting estimate is about 238 kcal/day; for an intact adult (1.4 × RER) about 277 kcal/day. Individual cats vary.

Do treats count toward a cat’s daily calories?

Yes. Treats are part of the daily total. The Merck Veterinary Manual advises keeping treats below 10% of total calorie intake.

How do I convert cat calories into grams of food?

Divide the calories by your food’s calorie density from its label. The Cat Food Calculator does this for grams, cups, cans or pouches using your actual food.

Which profile should I choose for my cat?

Choose the one that best describes your cat now: neutered adult, intact adult, inactive or obesity-prone adult, or growing kitten. Senior cats use the adult profile that fits them. If you’re unsure, ask your veterinarian.

Sources & Methodology

RER = 70 × kg^0.75. Estimated daily calories = RER × one factor from the table above; no other multipliers are applied. Results are rounded to the nearest kcal for display; calculations use full precision. The 0.3–15 kg input range is only a typing-error safeguard, not a biological limit. Not covered: pregnancy, nursing, weight-loss programmes and medical conditions.

Pet Nutrition Alliance: Calculating Calories Based on Pet Needs. RER equation; feline factors (neutered 1.2, intact 1.4, overweight-prone/inactive 1.0, growth 2–3); variation of up to 50%; kitten needs decreasing from around 4 months.
Merck Veterinary Manual: Daily Maintenance Energy Requirements for Dogs and Cats. Cat factors (intact 1.4, neutered 1.2, obesity prone 1, kittens 2.5 or free choice); calculations are a starting point.
Merck Veterinary Manual: Feeding Practices in Small Animals. Treats under 10% of total calorie intake; weight trends in older cats.
Merck Veterinary Manual (Cat Owners): Disorders of the Liver and Gallbladder in Cats. Hepatic lipidosis and its association with poor appetite.
WSAVA Global Nutrition Guidelines. Body and muscle condition assessment resources.

Educational purpose: PawCalcHub provides general estimates for education. They are not veterinary advice, diagnosis or treatment. This page has not been reviewed by a veterinarian. Talk to your veterinarian about your cat’s specific needs.