How Many Calories Does My Cat Need Per Day?

Figuring out exactly how many calories your cat needs isn't as simple as reading a pet food label. Every cat has unique energy requirements based on their weight, age, activity level, and whether they need to lose, maintain, or gain weight.

Understanding Resting Energy Requirement (RER)

The Resting Energy Requirement is the number of calories your cat needs simply to exist — to breathe, circulate blood, and maintain basic bodily functions while at rest. The veterinary formula for calculating RER is:

RER = 70 × (body weight in kg)^0.75

For example, a 5 kg (11 lb) cat has an RER of approximately 234 calories per day.

From RER to Daily Energy Requirement (DER)

The Daily Energy Requirement accounts for your cat's actual lifestyle and health status. We multiply the RER by a factor that reflects their situation:

• Neutered adult cat: RER × 1.2
• Intact adult cat: RER × 1.4
• Weight loss: RER × 0.8
• Weight gain: RER × 1.2–1.4
• Kitten (under 4 months): RER × 2.5
• Senior cat: RER × 1.1

A Practical Example

Let's calculate for Mittens, a neutered 6 kg adult cat who needs to lose weight:

1. Convert weight: 6 kg
2. Calculate RER: 70 × (6)^0.75 = 268 calories
3. Apply weight loss factor: 268 × 0.8 = 214 calories/day

Mittens should eat approximately 214 calories per day to safely lose weight.

Converting Calories to Food

Once you know the daily calorie target, check your cat food's calorie density (usually listed as kcal/cup or kcal/can). Divide your cat's daily calorie needs by the calorie density to find the appropriate portion size.

Important Considerations

• Never cut calories drastically: Cats should lose no more than 1-2% of their body weight per week
• Monitor regularly: Weigh your cat weekly and adjust portions as needed
• Account for treats: Treats should make up no more than 10% of daily calories
• Consult your vet: Especially important for cats with health conditions

The Bottom Line

Understanding your cat's calorie needs empowers you to make informed feeding decisions. Combined with regular weight monitoring and body condition assessments, you can help your feline companion achieve and maintain their ideal weight.