Vets work out a dog’s daily calories in two steps. First the resting energy requirement, RER = 70 × (weight in kg)^0.75 kcal a day – the energy for a dog lying still. Then a factor for its life: 1.6 for a typical neutered adult, 1.8 for an intact one, less for a couch potato, more for a puppy or a working dog. Divide by the energy of the food and you have the portion.
Example: a 10 kg (22 lb) spayed beagle. RER = 70 × 10^0.75 = 394 kcal; × 1.6 = 630 kcal a day. Her dry food has 3,700 kcal/kg, so 630 ÷ 3.7 = 170 g a day, two meals of 85 g – or 1.8 cups of a food with 350 kcal per cup.
Life-stage factors
| Your dog | Factor × RER |
|---|---|
| Neutered or spayed adult | 1.6 |
| Intact adult | 1.8 |
| Inactive, or gains weight easily | 1.2–1.4 (the calculator uses 1.3) |
| Losing weight (at the target weight) | 1.0 |
| Puppy under 4 months | 3.0 |
| Puppy 4 months to adult size | 2.0 |
| Working or very active dog | 2.0 and up |
Daily calories and food by weight
Neutered adults; dry food of 3,700 kcal/kg and 350 kcal per cup.
| Weight | Calories a day | Dry food a day | Cups | Lazy dog | Intact dog |
|---|---|---|---|---|---|
| 2 kg (4 lb) | 188 kcal | 51 g | 0.5 | 153 kcal | 212 kcal |
| 5 kg (11 lb) | 374 kcal | 101 g | 1.1 | 304 kcal | 421 kcal |
| 10 kg (22 lb) | 630 kcal | 170 g | 1.8 | 512 kcal | 709 kcal |
| 15 kg (33 lb) | 854 kcal | 231 g | 2.4 | 694 kcal | 960 kcal |
| 20 kg (44 lb) | 1,059 kcal | 286 g | 3.0 | 861 kcal | 1,192 kcal |
| 30 kg (66 lb) | 1,436 kcal | 388 g | 4.1 | 1,166 kcal | 1,615 kcal |
| 40 kg (88 lb) | 1,781 kcal | 481 g | 5.1 | 1,447 kcal | 2,004 kcal |
| 50 kg (110 lb) | 2,106 kcal | 569 g | 6.0 | 1,711 kcal | 2,369 kcal |
Notice that a 40 kg dog needs less than four times what a 10 kg dog needs, not four times as much: energy grows with weight to the power 0.75. That is why a single “grams per kilo” rule overfeeds big dogs and underfeeds small ones.
Reading the bag
- US and Canada: the label gives “Calorie content (ME)” in kcal/kg and kcal per cup – both go straight into the calculator.
- Europe, UK and elsewhere: look for “metabolizable energy” in kcal/100 g or kcal/kg (multiply kcal/100 g by 10), sometimes in MJ/kg (multiply by 239).
- Wet food: usually 700–1,200 kcal/kg, so the grams are three to five times higher. When you mix wet and dry, share the calories between them.
- Treats: keep them under 10% of the calories, and take them off the meals.
Weigh, then adjust
A single dog can need noticeably more or less than the average. Weigh yours every two to four weeks at first. If it gains, cut the portion by about 10%; if it loses, add 10%. You should be able to feel its ribs under a thin layer of fat, and see a waist from above. A sudden change in appetite or weight is a reason to see the vet. To track your dog’s age in human years, see the dog age calculator.
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Frequently asked questions
How much should a 20 kg (44 lb) dog eat a day?
About 1,060 kcal if it is a neutered adult with normal activity: 286 g of a dry food with 3,700 kcal/kg, or 3 cups of a food with 350 kcal per cup. A lazy dog of the same weight needs about 860 kcal, an intact one about 1,190.
Why is the amount on the bag different?
A bag's chart covers a broad range of dogs and cannot know whether yours is neutered, young or lazy. The calculator starts from your dog's own life stage. Both are starting points: what your dog's waist and ribs look like after a month tells you which is right.
How many cups of dog food is that?
Divide the calories by the kcal per cup printed on the bag (US labels give both kcal/kg and kcal/cup). Cups mean an 8 fl oz measuring cup, level, not a mug. A kitchen scale is more accurate, because what a cup weighs depends on the size and density of the kibble.
How much should a puppy eat?
Much more per kilogram than an adult: three times its resting energy until about 4 months, then twice until it is grown. A 4 kg puppy of 3 months needs about 590 kcal a day, almost twice a 4 kg adult. Split it into three or four meals, and follow the puppy food's chart and your vet's advice.
Sources
- WSAVA Global Nutrition Committee: Global Nutrition Guidelines and calorie tools
- Pet Nutrition Alliance: Calculating your pet's calorie needs
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