Free Tool

Cat Food Calculator

Science-based daily feeding calculation

Based on NRC 2006, WSAVA 2020, AAHA 2021 Guidelines

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Enter your cat's details

More accurate than package guidelines

4.5
Neutered cats need ~25% fewer calories (MER ×1.0 vs ×1.4)

The Science Behind Our Calculator

Kleiber's Law (RER Formula)

In the 1930s, scientist Max Kleiber discovered that metabolic rate scales with body weight to the power of 0.75, not linearly. This means a cat twice the weight doesn't need twice the calories. The formula RER = 70 × BW^0.75 is now the gold standard used by NRC, WSAVA, and AAHA.

RER = 70 × weight0.75

The Senior Cat U-Curve Paradox

Contrary to popular belief, cats 12+ years often need MORE calories, not less. Their digestive efficiency drops by up to 33%, meaning they absorb fewer nutrients from the same food. This creates a U-shaped curve where middle-aged cats (7-11) need the least, but seniors need more.

Why Neutering Changes Everything

Research shows neutering reduces metabolic rate by 24-33%. Sex hormones naturally suppress appetite while boosting metabolism. After neutering, cats burn fewer calories but feel hungrier - a double whammy that explains why 60%+ of pet cats are overweight.

MER Coefficient Reference Table

Based on NRC 2006, WSAVA 2020, and AAHA 2021 guidelines

Life StageConditionMER CoefficientNotes
Baby Kitten (<4mo)-×2.5-3.0Rapid growth, frequent feeding needed
Kitten (4-12mo)-×2.0Still growing but slowing down
Adult (1-6yr)Intact×1.4-1.6Higher metabolism due to sex hormones
Adult (1-6yr)Neutered Indoor×1.0Modern pet cat default - prevents obesity
Adult (1-6yr)Neutered Active×1.2Active daily play or outdoor access
Mature (7-11yr)-×1.0-1.1Metabolic low point, strict calorie control
Senior (12+yr)Normal×1.1-1.2Digestive efficiency decreasing
Senior (12+yr)Thin/Underweight×1.4-1.6Need more to maintain muscle mass
Weight Loss-×0.8Based on IDEAL weight, not current

Quick Calorie Reference by Weight

Current Weight (kg)RERNeutered Indoor (×1.0)Intact/Active (×1.4)
3 kg160 kcal160 kcal224 kcal
4 kg198 kcal198 kcal277 kcal
5 kg234 kcal234 kcal328 kcal
6 kg268 kcal268 kcal375 kcal
7 kg301 kcal301 kcal421 kcal
8 kg333 kcal333 kcal466 kcal
* The difference between neutered indoor (×1.0) and intact active (×1.4) can be 40% - this is why package guidelines often overfeed neutered cats.

Frequently Asked Questions

The amount depends on your cat's weight, age, activity level, and neutered status. Most adult neutered indoor cats need about 200-250 kcal per day. Use our calculator based on the NRC/WSAVA formula for a personalized recommendation.
Research shows neutering reduces metabolic rate by 24-33%. Sex hormones (estrogen/testosterone) suppress appetite and boost metabolism. After neutering, cats need fewer calories but feel hungrier - this is the #1 cause of obesity in pet cats.
Package guidelines are designed for "all life stages" including active intact cats (MER ×1.4). For legal safety, manufacturers recommend higher amounts. For a typical neutered indoor cat, our calculator uses the correct ×1.0 coefficient - package amounts may be 40% too high!
Surprisingly, NO! Cats show a unique "U-curve" pattern. Middle-aged cats (7-11 years) need less food, but cats 12+ years actually need MORE calories because their digestive efficiency drops by up to 33%. Thin senior cats may need 1.4-1.6× RER.
RER (Resting Energy Requirement) is the calories needed at rest, calculated as 70 × weight^0.75 (Kleiber's Law). MER (Maintenance Energy Requirement) = RER × life stage coefficient. This scientific approach is more accurate than simple weight-based calculations.
Always use a digital kitchen scale! Research shows measuring cup portions can vary by -20% to +80% depending on the person and kibble density. A 20 kcal daily error equals ~5g of dry food - enough to cause significant weight change over a year.
Calculate based on IDEAL weight (not current weight) with ×0.8 coefficient. Aim for 0.5-2% weight loss per week. NEVER cut food by more than 50% - this can cause fatal hepatic lipidosis (fatty liver). Use our Weight Loss mode for safe calculations.
Weigh your cat every 2-4 weeks and adjust portions based on trends. Our calculation is a starting point - the true precision comes from the "calculate → weigh → feedback → adjust" cycle. Seasonal changes, activity levels, and health status all affect needs.

Healthy eating = healthy digestion

A well-fed cat produces less smelly waste. Pair good nutrition with Liger's premium tofu litter for the cleanest litter box experience.

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