Dog Food Calculator Widget

Let readers turn a bag label into a portion: the dog's weight and life stage give its daily calorie need, and the food's kcal per cup or per kilogram turns that into a measured amount, with room left for treats under the WSAVA 10% limit.

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How it works

Resting energy requirement (RER) is the energy a dog uses at rest in a comfortable environment: 70 multiplied by body weight in kilograms raised to the power 0.75. A 10 kg dog needs about 394 kcal at rest. Daily maintenance energy is RER times a factor for life stage from the Merck Veterinary Manual: 1.6 for a neutered adult (630 kcal for that dog), 1.8 intact, 1.4 for an inactive or gain-prone adult, 3.0 for a puppy under four months and 2.0 from four months to adulthood; a custom factor from the vet can be entered instead. The chosen treat share, at most 10% following WSAVA guidance, is subtracted, and the remaining calories are divided by the food's energy density - kcal per cup for a measuring-cup feeder, kcal per kg for anyone using kitchen scales. Pounds are converted at 0.4536 kg.

Calculation method

  • RER (kcal/day) = 70 x (body weight in kg)^0.75
  • Daily energy = factor x RER; factor 1.6 neutered adult, 1.8 intact adult, 1.4 inactive or obesity prone, 3.0 puppy under 4 months, 2.0 puppy 4 months to adult
  • Treat calories = daily energy x treat % (0-10%); food calories = daily energy - treat calories
  • Cups per day = food calories / kcal per cup; grams per day = food calories / kcal per kg x 1,000

Worked examples

Neutered 10 kg dog on kibble by weight

Inputs: 10 kg; neutered adult; 3,600 kcal/kg; treats 10%

Result: 157 g of food a day; 630 kcal need; RER 394 kcal; 63 kcal of treats

70 x 10^0.75 = 393.6; x 1.6 = 629.8; 90% of that is 566.8 kcal; / 3.6 = 157.5 g.

Active intact 44 lb dog by the cup

Inputs: 44 lb (19.96 kg); intact adult; 400 kcal/cup; no treats

Result: 2.97 cups a day; 1,190 kcal; RER 661 kcal

19.96^0.75 = 9.45, x 70 = 661, x 1.8 = 1,190 kcal, / 400 = 2.97 cups.

An informational estimate based on published guidance, not veterinary advice or a diagnosis. Every animal is different - ask your veterinarian about your pet's health, diet and care.

Limitations

  • Individual needs differ widely with breed, coat, climate and activity; use the result as a first portion and adjust by body condition.
  • Not for pregnancy, lactation, illness or working dogs with high energy demands.
  • Cup volumes vary between scoops and kibble shapes; weighing is more reliable.

Where publishers use it

  • A dog-food brand's product page so buyers see the daily portion for their dog's weight
  • A veterinary practice's weight-management page as a starting point before a consultation
  • A raw or fresh-food subscription site estimating how much each delivery must contain
  • A puppy-training blog showing how energy needs fall after four months
  • A dog walker's or sitter's info page so owners can leave accurate feeding notes

Questions

Where do I find the kcal per cup?

On most bags the calorie statement is printed near the guaranteed analysis as 'kcal/kg' and 'kcal/cup' (metabolizable energy). Dry foods are commonly 3,000-4,500 kcal/kg. If only kcal/kg is printed, choose that option and weigh the food with kitchen scales - it is more accurate than a cup anyway.

Why use RER to the power 0.75 instead of a simple per-kg figure?

Energy use scales with metabolic body size, not weight. A 40 kg dog weighs four times a 10 kg dog but needs only about 2.8 times the calories (40^0.75 / 10^0.75 = 2.83), which the exponent captures.

My dog is overweight. Which weight do I enter?

Use the target weight agreed with your vet, not the current weight, and the 1.4 factor or a custom factor your vet gives you. Feeding for the current weight keeps the dog at that weight.

How many treats can I give?

WSAVA advises keeping treats under 10% of daily calories. With the treat box at 10%, a dog needing 630 kcal has a 63 kcal treat budget and the main food is reduced to 567 kcal.

Is the factor for puppies right for large breeds?

The Merck factors of 3 x RER under four months and 2 x RER after are general guides. Large and giant breed puppies are prone to developmental bone disease if overfed, so their growth curve should be watched closely by a vet.

Does this cover pregnancy or nursing?

No. Pregnant and lactating dogs need much more energy, especially in late pregnancy and peak lactation; use the custom factor only with figures from your vet.

Sources

  1. Nutritional Requirements of Small Animals - Merck Veterinary Manual . RER = 70 x (body weight in kg)^0.75; maintenance factors for dogs (intact 1.8, neutered 1.6, obesity prone 1.4, puppies under 4 months 3, over 4 months 2) and cats (intact 1.4, neutered 1.2, obesity prone 1, kittens 2.5). Checked 2026-10-01.
  2. Feeding treats to your dog (WSAVA Global Nutrition Toolkit) - World Small Animal Veterinary Association . Treats should make up less than 10% of a dog's daily calorie intake. Checked 2026-10-01.

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A2Z Tools Dog Food Calculator
https://a2z.tools/embed/dog-food-calculator

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