Feeding estimate

Pet Food Portion Calculator

Estimate how much to feed your dog or cat each day, based on weight and activity level — using the same RER/MER math vets use as a starting point.

0RER (kcal/day)
0MER (kcal/day)
0cups/day
0per meal
This is a general estimate using standard RER/MER formulas — it is not veterinary advice. Actual calorie needs vary by breed, metabolism, age and health. Ask your vet before making major feeding changes, especially for puppies, kittens, seniors or pets with a medical condition.

Why estimate portions this way

Feeding guides on bags are averages for an "average" animal — they rarely account for your specific pet's weight, activity level or your food's actual calorie density. A quick calorie-based estimate gets you much closer, in seconds.

Vet-style formula

Uses the same RER/MER approach vets use as a starting point for calorie needs.

Any food, any unit

Works with cups or grams, and lets you enter your exact food's caloric density.

Meal-ready split

Instantly divides the daily total into 2 or 3 even meals.

How to use the portion calculator

  1. Pick dog or catSelect which type of pet you're feeding.
  2. Enter weightType your pet's weight and choose lb or kg.
  3. Set activity & food detailsChoose an activity level and enter your food's caloric density.
  4. Read the splitSee the daily total and the per-meal amount for 2 or 3 meals.

About the RER/MER method

Resting Energy Requirement (RER) estimates the calories an animal burns simply staying alive at rest, calculated here as 70 × (weight in kg) raised to the power of 0.75 — a formula widely used in veterinary nutrition. Maintenance Energy Requirement (MER) then multiplies RER by an activity factor to approximate real daily needs: roughly 1.2× for a low-activity or weight-loss goal, 1.6× for a typical, moderately active pet, and 2.0× for a highly active animal. Dividing the resulting daily calories by your food's caloric density — kcal per cup or per 100 grams, both printed on most bags and cans — converts the number into something you can actually scoop out. These factors are general estimates, not a substitute for professional guidance, and pets with specific medical conditions, unusual metabolisms, or those who are pregnant, nursing, growing or seniors may need very different amounts.

RER formula

70 × (weight in kg)0.75, a standard veterinary starting point.

Activity factors

1.2× low, 1.6× moderate, 2.0× high — general multipliers, not exact science.

Not medical advice

Always confirm feeding changes with your veterinarian, especially for at-risk pets.

Pet food portion FAQ

How accurate is this calculator?

It's a general estimate using standard veterinary RER and MER formulas, not a precise prescription. Actual needs vary by breed, metabolism, spay or neuter status, and health conditions, so always check with your vet, especially for puppies, kittens, seniors or pets with medical conditions.

What is RER and MER?

RER, Resting Energy Requirement, is roughly the calories an animal burns at rest. MER, Maintenance Energy Requirement, multiplies RER by an activity factor to estimate typical daily calorie needs.

Where do I find my food's caloric density?

Check the bag or can label for kcal per cup or kcal per kg, dividing by 10 for kcal per 100g. If it's not listed, contact the manufacturer. The default of 350 kcal per cup here is just a common approximation for dry kibble.

Should I split meals into 2 or 3?

Either works. More frequent, smaller meals can aid digestion, but total daily calories matter more than the split. Choose whatever fits your schedule and your vet's advice.

Does this work for cats too?

Yes, the same formula applies to both dogs and cats, though actual feeding guidelines can differ. Treat this as a starting estimate, not a substitute for veterinary guidance.

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