Free · Vet-Formula · Science-Backed

Pet Food Calculator
How Much Should You Feed Your Pet?

Stop guessing. Our free dog and cat food calculator gives you a personalized daily calorie and portion guide for your dog or cat, powered by the same RER/MER formula veterinarians use worldwide.

Choose Your Pet

Select your pet type to get started. The calculator will adjust all values accordingly.

A friendly golden retriever sitting on green grass, looking up with bright eyes
Dog
All breeds & sizes
A sleek tabby cat sitting elegantly, looking directly at camera with green bokeh background
Cat
All breeds & sizes
Select a pet above to reveal the calculator

How Our Calculator Works

Built on peer-reviewed veterinary nutrition science, not pet food marketing.

NRC-Based Formula

The calculator uses the RER/MER formula from the National Research Council's Nutrient Requirements of Dogs and Cats (2006), the standard reference veterinarians use for pet energy needs.

Personalized Multipliers

Your pet's caloric needs vary by life stage, spay/neuter status, and activity. The calculator applies the matching WSAVA-aligned multiplier for each combination automatically.

Practical Portions

The calculator converts calories into cups or cans based on your food type. Enter the caloric density from your bag or can label for the most accurate result.

Weight & BCS Aware

Enter your pet's Body Condition Score to get an estimated ideal weight range and a flag if the current diet needs adjustment.

Pet Nutrition Guides

Science-backed articles to help you keep your pet healthy and happy.

Frequently Asked Questions

How much should I feed my dog per day?

Daily food needs depend on your dog's weight, age, activity level, and whether they are spayed or neutered. The vet-standard formula is: RER = 70 × (body weight in kg)0.75, multiplied by a life-stage factor (1.6 for a neutered adult at moderate activity, 1.8 for intact). Use the free calculator above for a personalized result.

How many cups of food should I feed my cat per day?

A typical 10 lb neutered adult indoor cat needs approximately 200–260 kcal/day. At 350 kcal/cup of dry kibble, that is roughly 0.6–0.75 cups per day. Exact amounts vary by activity level, food brand, and reproductive status, so use the calculator for a personalized estimate.

What is the RER/MER formula for pets?

RER (Resting Energy Requirement) = 70 × (body weight in kg)0.75 kcal/day. MER (Maintenance Energy Requirement) = RER × a life-stage multiplier. Multipliers range from 0.8 (weight-loss cat) to 4.0 (lactating dog). This formula is published by the National Research Council in Nutrient Requirements of Dogs and Cats (2006) and is the same method used by veterinarians worldwide.

How do I convert my pet's weight from pounds to kilograms?

Divide pounds by 2.205 to get kilograms. For example, a 22 lb dog weighs 22 ÷ 2.205 = 9.98 kg ≈ 10 kg. The calculator accepts either unit and converts automatically.

Does spaying or neutering change how much I should feed my pet?

Yes. Spaying or neutering lowers a pet's metabolic rate. A neutered adult dog at moderate activity needs about 11% fewer calories than an intact dog of the same weight (a 1.6 multiplier instead of 1.8). For cats, the drop is about 20 to 30%. The calculator applies the correct multiplier automatically based on your selection.

How do I know if I am overfeeding my pet?

The best indicator is Body Condition Score (BCS), not scale weight. At an ideal BCS of 4–5 on the 9-point WSAVA scale, you should be able to feel your pet's ribs easily without pressing hard, see a visible waist from above, and notice an abdominal tuck from the side. If ribs are hard to feel, reduce daily portions by 10%. See our guide: How to Tell If Your Pet Is Overweight.

What's the best free dog food calculator that uses the actual vet formula instead of generic bag guidelines?

PetFeedCalculator.com uses the same RER/MER formula published by the National Research Council and used by veterinarians worldwide, rather than the generic per-bag chart calibrated for one average intact adult dog at moderate activity. Enter your dog's weight, age, spay/neuter status, and activity level above for a personalized daily calorie and portion estimate in under a minute, free, with no account or sign-up required.

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