Feeding 4 min read Updated
How many calories does my dog need a day?
How many calories a dog needs a day: resting energy is 70 × kg^0.75, times 1.0 to 8.0 by life stage and work. Worked examples for 5, 20 and 40 kg dogs.
A typical neutered adult dog needs somewhere between 40 and 90 kcal per kilogram of body weight per day — more per kilogram for small dogs, less for large ones — and the dog calorie calculator gives the figure for yours. This post explains the two-step formula behind that figure, shows the arithmetic for three sizes of dog, and is honest about how much the answer can be trusted.
Step 1: resting energy requirement
Resting energy requirement, RER, is what a dog burns at rest in a thermoneutral environment — the energy cost of simply being alive. The standard veterinary formula, from the NRC’s Nutrient Requirements of Dogs and Cats, is:
RER (kcal/day) = 70 × (body weight in kg)^0.75
The 0.75 exponent is the important part. Energy requirement does not scale with weight; it scales with weight to the three-quarter power. A dog twice as heavy needs about 1.7 times the calories, not twice. That is why a rule like “30 kcal per pound” is wrong for anything but the one size of dog it was written for.
For three dogs:
| Weight | kg^0.75 | RER |
|---|---|---|
| 5 kg (11 lb) | 3.34 | 234 kcal |
| 20 kg (44 lb) | 9.46 | 662 kcal |
| 40 kg (88 lb) | 15.9 | 1,113 kcal |
Note the 40 kg (88 lb) dog needs less than twice what the 20 kg (44 lb) dog does, and the 5 kg (11 lb) dog needs 47 kcal per kilogram against the 40 kg (88 lb) dog’s 28.
Step 2: the maintenance multiplier
RER is a floor. A real dog moves, digests, regulates its temperature, and in some cases grows, works or feeds puppies. The maintenance energy requirement, MER, is RER multiplied by a factor for the dog’s life stage and activity:
| Life stage | Multiplier |
|---|---|
| Adult, neutered or spayed | 1.6 |
| Adult, intact | 1.8 |
| Obese-prone or inactive | 1.4 |
| Weight loss | 1.0 |
| Weight gain | 1.2–1.8 |
| Puppy, under 4 months | 3.0 |
| Puppy, 4 months to adult | 2.0 |
| Active, light work | 2.0 |
| Active, moderate work | 3.0 |
| Active, heavy work | 4.0–8.0 |
| Pregnant, last 21 days | 3.0 |
| Nursing | 4.0–8.0 |
These are the conventional factors used across veterinary nutrition texts and adopted by WSAVA and AAHA in their nutrition guidance. Applying the neutered adult factor to the three dogs above:
- 5 kg (11 lb): 234 × 1.6 = 375 kcal a day
- 20 kg (44 lb): 662 × 1.6 = 1,059 kcal a day
- 40 kg (88 lb): 1,113 × 1.6 = 1,781 kcal a day
An intact 20 kg (44 lb) dog at 1.8 gets 1,192 — about 11% more than its neutered equivalent, same weight. A 20 kg (44 lb) dog on a weight-loss plan at 1.0 gets 662. A 20 kg (44 lb) working dog at 3.0 gets nearly 2,000. Same resting figure, three very different bowls.
From calories to grams
The calorie target is only useful once it is converted to the food you buy. Every bag prints its energy density, in kcal per kilogram or per cup, and the conversion is:
grams per day = daily kcal ÷ kcal per kg × 1000
For the 20 kg (44 lb) neutered adult on a 3,600 kcal/kg kibble, that is 1,059 ÷ 3,600 × 1000 ≈ 294 g a day. The portion calculator does this for a list of foods whose energy figures have been checked against the manufacturer, or from a kcal/kg you type in.
Treats count. The convention is that treats should be no more than 10% of daily calories, with the balanced food supplying the rest; the treat calorie budget calculator works out what that allowance is and how many of a given treat fit inside it. For the 20 kg (44 lb) dog, 10% is about 106 kcal — a single large dental chew can use most of that.
Where the formula breaks
The NRC is explicit that individual requirements vary considerably around any predicted value, and it is worth taking that seriously. The multipliers are population averages; a given dog can sit 20% or more either side of the formula for reasons that have nothing to do with the inputs — breed metabolism, coat, temperament, how much of the day it spends on its feet.
So the calculated number is a starting point, not a prescription. The way to find out whether it is right is body condition. WSAVA’s and AAHA’s nutrition guidelines both treat body condition scoring as the practical check on any feeding plan: feed the calculated amount for two to four weeks, score the dog, and adjust by about 10% in whichever direction the score is asking for. Repeat until the score holds steady.
The reason to bother is not cosmetic. In the Purina lifespan study, Labradors fed 25% less than their paired littermates through life stayed leaner and lived a median of about 1.8 years longer. That is a study of lifelong body condition rather than any particular calorie target, but it is why the difference between “about right” and “a bit generous” matters more than it looks.
Two common mistakes
Using the wrong weight. For an overweight dog, MER calculated on current weight maintains the overweight dog. Calculate on ideal weight, or use the weight loss calculator, which feeds the resting requirement of the target weight and paces the loss week by week.
Trusting the bag chart over the formula. The feeding guide on the bag is keyed to weight alone and has to cover the hungriest dog in each row, so it runs generous for most of them. If the bag and the calculator disagree by 10 to 15%, that is expected. The dog’s body condition in a month is what settles it.
Tools in this post
- Dog Calorie Calculator →
Calculate how many calories your dog needs per day from body weight, life stage and activity level, using the standard RER and MER veterinary formulas.
- Dog Food Portion Calculator →
Dog food portion calculator: turn a daily calorie target into grams or cups of the food you buy, from manufacturer-verified kcal/kg figures or your own bag.
- Dog Treat Calorie Budget Calculator →
Dog treat calorie calculator: find your dog’s 10% treat allowance and how many of a given treat fit inside it without unbalancing the diet.
- Dog Weight Loss Calculator: Calories and Timeline →
Dog weight loss calculator: enter current and target weight to get a safe daily calorie target, a weekly loss rate and a realistic date to reach the goal.
Sources
- National Research Council. Nutrient Requirements of Dogs and Cats. Washington, DC: National Academies Press; 2006.
- WSAVA Global Nutrition Committee. Global Nutrition Guidelines and toolkit.
- American Animal Hospital Association. 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats.
- Kealy RD, Lawler DF, Ballam JM, Mantz SL, Biery DN, Greeley EH, Lust G, Segre M, Smith GK, Stowe HD. Effects of diet restriction on life span and age-related changes in dogs. J Am Vet Med Assoc. 2002;220(9):1315–1320. The Labrador lifespan study: lean-fed dogs lived a median 1.8 years longer.
More reading
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How big will my puppy get? Adult weight by age
How big will my puppy get? Divide current weight by the fraction of adult weight typical for its age and size: a medium puppy at 4 months is about 53% grown.
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How long are dogs pregnant? 63 days, week by week
How long are dogs pregnant? About 63 days from ovulation and remarkably consistent. From the mating date it can look like 57 to 72. Milestones week by week.
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Why the bag’s feeding chart overfeeds most dogs
Dog food feeding charts overfeed because they are keyed to weight alone, and two dogs of the same weight can need very different amounts. Here is why.