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Pet Food Portion Calculator

Find out exactly how much to feed your pet based on veterinary-grade nutrition formulas. Works for dogs, cats, rabbits, guinea pigs, and birds.

Pet Food Portion Calculator Tool

1 Your Pet 2 Details 3 Activity 4 Food 5 Results

What type of pet do you have?

Select your pet's species to get started.

Tell us about your pet

We'll use these details to calculate the perfect portion size.

years
months

How does your pet's body look? Select the closest match.

Life stage & activity level

We'll fine-tune the calculation based on your pet's lifestyle.

Auto-detected from age. Change if needed.

What food do you feed?

Select your food type and brand so we can calculate the exact portion.

How Much Should I Feed My Dog? The Science Explained

Every pet food bag includes a feeding guide, but those charts are notoriously imprecise. They are designed to cover the broadest possible range of animals and tend to overestimate portions by 20 to 30 percent. The reason is simple: food manufacturers have a financial incentive for you to use more product. Veterinary nutritionists use a far more accurate two-step method based on your pet's Resting Energy Requirement (RER) and Maintenance Energy Requirement (MER), and that is exactly what our calculator does.

RER is the number of calories your pet needs at complete rest, calculated using the formula 70 multiplied by their body weight in kilograms raised to the power of 0.75. MER then adjusts that baseline by a life stage and activity multiplier. A desexed adult dog has a multiplier of roughly 1.6, while an intact adult is closer to 1.8. Puppies under four months need three times their RER, and lactating dogs can require up to four to eight times their RER depending on litter size. These multipliers are drawn from peer-reviewed veterinary nutrition guidelines and are the same formulas used by board-certified veterinary nutritionists in clinical practice.

Body Condition Score (BCS) is the other critical variable most feeding guides ignore entirely. Assessed on a 1-to-9 scale, BCS tells you whether your pet is underweight, ideal, or overweight based on visible and palpable body fat. A dog with a BCS of 7 out of 9 is carrying roughly 20 percent excess body fat and should be fed for their ideal weight, not their current weight. Our calculator adjusts portions based on your pet's BCS to account for this, which is something no feeding chart on a bag can do.

The final piece of the puzzle is the caloric density of your specific food. Dry kibble typically ranges from 300 to 400 kcal per 100 grams, while wet food is usually 80 to 120 kcal per 100 grams due to its high moisture content. Raw and fresh diets fall somewhere in between. By combining your pet's MER with the exact caloric density of their food, our calculator converts the daily calorie target into precise grams and cups, giving you a genuinely useful number rather than a vague range.

Need Personalised Advice?

This calculator provides evidence-based estimates, but every pet is unique. If your pet has a medical condition, is significantly over or underweight, or needs a prescription diet, a veterinary nutritionist can create a tailored feeding plan. Use our directory to find a trusted vet near you.

Find a Vet Near You →

Frequently Asked Questions

The amount depends on your dog's weight, age, activity level, and whether they are desexed. As a rough guide, most adult dogs need between 2 and 3 percent of their body weight in food per day, but calorie-based calculations are far more accurate. Our calculator uses the veterinary RER/MER formula to give you a precise daily amount in grams and cups for your specific food.

An average 4 kg adult cat needs approximately 200 to 250 calories per day, but this varies with age, activity, and desexing status. Indoor cats and desexed cats typically need fewer calories. Enter your cat's details into our calculator for a precise portion tailored to their food's caloric density.

Bag feeding guides use broad weight ranges and do not account for age, activity level, body condition, or desexing status. Studies show they tend to overestimate portions by 20 to 30 percent. Our calculator uses the same RER/MER formula that veterinary nutritionists use in clinical practice, adjusted for your pet's individual profile.

Use the Body Condition Score (BCS) system. At an ideal score of 4 to 5 out of 9, you should be able to feel your pet's ribs easily without pressing hard, see a visible waist when viewed from above, and notice a tummy tuck when viewed from the side. If ribs are hard to feel or the waist is absent, your pet may be overweight.

Puppies need significantly more calories per kilogram than adult dogs because they are growing rapidly. Puppies under four months need roughly three times their RER, while those aged four to twelve months need about twice their RER. Feed puppies three to four meals per day until six months, then transition to twice daily. Our calculator adjusts automatically based on your puppy's age.

For safe weight loss, feed your pet for their ideal body weight rather than their current weight, and reduce portions gradually by no more than 10 to 15 percent. Rapid calorie restriction can cause serious health problems, especially in cats where it can trigger hepatic lipidosis. Consult your vet before starting any weight loss plan, and use our calculator with a BCS-adjusted target.

Yes, mixing wet and dry food is perfectly fine and can offer benefits like increased hydration and palatability. The key is to calculate the total daily calories from both food types combined. Our calculator's mixed feeding mode lets you set a dry/wet split ratio and calculates the correct gram amount for each food type so the combined total meets your pet's calorie needs.

Treats should make up no more than 10 percent of your pet's daily calorie intake. For an average adult dog eating 800 calories per day, that means no more than 80 calories in treats. Remember to subtract treat calories from their main meal portions to avoid overfeeding. Many commercial treats are surprisingly calorie-dense, so check the packaging.

A rabbit's diet should be approximately 80 percent unlimited grass hay, 10 to 15 percent fresh leafy greens, and only 5 percent high-quality pellets. For pellets, the general guideline is about one quarter cup per 2 kg of body weight per day. Our calculator provides a species-specific breakdown covering hay, greens, and pellet portions based on your rabbit's weight and age.

Most vets recommend feeding adult cats two to three measured meals per day rather than free-feeding from an always-full bowl. Portion-controlled meals help prevent obesity, make it easier to monitor appetite changes, and allow you to track exactly how much your cat eats. Kittens under six months should be fed three to four times daily due to their higher energy needs.