# How many dog calories per day?

Estimates a dog’s daily calories from its weight and life stage: the resting energy requirement 70 × kg^0.75 times the Merck Veterinary Manual factor, with cups or cans of food.

- Page: https://www.acalculator.org/biology/dog-calorie-calculator
- JSON spec: https://www.acalculator.org/biology/dog-calorie-calculator.json
- Version: da11bd777eff

## Default answer

Example with the default inputs (Dog’s weight 30 lb, Life stage Neutered adult (× 1.6)): A 30 lb dog needs about 794 calories a day at 1.6 × RER.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| w | Dog’s weight | Your dog’s body weight now (use the ideal weight your vet gives for a weight-loss plan). |
| stage | Life stage | The life stage or activity, which sets the factor on the resting energy. |
| food | Food calories per cup or can | From the food label, in kcal per cup or per can. Leave empty to skip. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| daily | Calories per day | RER × the life-stage factor. |
| rer | Resting energy (RER) | 70 × body weight in kg raised to the power 0.75. |
| factor | Life-stage factor | The Merck Veterinary Manual multiplier for this life stage. |
| portions | Cups or cans per day | Calories per day ÷ the food’s calories per cup or can. |
| linear | RER by the linear formula | 30 × kg + 70, which Merck gives for dogs over 2 kg and under 45 kg; shown for comparison only. |

## Method

RER = 70 × (body weight in kg)^0.75 kcal a day; calories per day = RER × the life-stage factor (neutered adult 1.6, intact adult 1.8, inactive or obesity prone 1.4, puppy under 4 months 3.0, puppy 4 months to adult 2.0); cups or cans = calories ÷ the food’s calories per cup or can.

## Assumptions

- The factors are the Merck Veterinary Manual’s for healthy dogs. Dogs of the same weight can need 30% more or less, so the result is a starting point: weigh your dog every few weeks and adjust.
- Working, pregnant, nursing, sick and overweight dogs need a vet’s plan; this page has no factor for them.
- This page is for information only and is not veterinary advice.

## Worked examples

1. w = 10, stage = neutered gives rer = 393.638928, daily = 629.822284, linear = 370. Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75 or 30 × BW(kg) + 70 for > 2 kg and < 45 kg; puppies under 4 months 3 × RER, over 4 months 2 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals.
2. w = 13.607771, stage = intact, food = 350 gives rer = 495.950448, daily = 892.710806, portions = 2.550602. Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75 or 30 × BW(kg) + 70 for > 2 kg and < 45 kg; puppies under 4 months 3 × RER, over 4 months 2 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals.
3. w = 5, stage = young gives rer = 234.059107, daily = 702.17732, factor = 3. Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75 or 30 × BW(kg) + 70 for > 2 kg and < 45 kg; puppies under 4 months 3 × RER, over 4 months 2 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals.
4. w = 50, stage = prone gives rer = 1,316.211083, daily = 1,842.695516. Source: Merck Veterinary Manual, Nutritional Requirements of Small Animals (S. L. Sanderson, reviewed Nov 2023): RER = 70 × BW(kg)^0.75 or 30 × BW(kg) + 70 for > 2 kg and < 45 kg; puppies under 4 months 3 × RER, over 4 months 2 × RER, https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals.

## FAQ

### How many calories does a dog need a day?

A 30 lb (13.6 kg) neutered adult needs about 70 × 13.6^0.75 × 1.6 = 794 kcal a day; the same dog intact needs about 893 kcal. A 10 kg neutered dog needs about 630 kcal.

### What is RER?

The resting energy requirement: the calories a dog burns at rest in a comfortable room. RER = 70 × body weight in kg raised to the power 0.75. A 10 kg dog’s RER is about 394 kcal.

### Which factor fits my dog?

The Merck Veterinary Manual gives 1.6 × RER for a neutered adult, 1.8 for an intact adult and 1.4 for an obesity-prone dog. Puppies need 3 × RER until 4 months old and 2 × RER from then until they are grown.

### How much food is that?

Find the kcal per cup or per can on the food label and type it. A 30 lb intact dog at 893 kcal a day, on food with 350 kcal per cup, needs about 2.55 cups a day, split into meals. Count treats too.

### Why are there two RER numbers?

Merck gives two formulas. 70 × kg^0.75 works for any weight; the linear 30 × kg + 70 is a shortcut for dogs over 2 kg and under 45 kg. The page uses the first and shows the second for comparison.

### How do I feed a dog that needs to lose weight?

Ask your vet for a target weight and a plan, and weigh the dog often. Dogs of the same weight can need 30% more or fewer calories, so any formula is only a starting point.

## Sources

- Merck Veterinary Manual, Nutritional Requirements of Small Animals, by Sherry Lynn Sanderson (full review Nov 2023): RER = 70 × BW(kg)^0.75, or 30 × BW(kg) + 70 for animals over 2 kg and under 45 kg; daily maintenance energy for dogs: intact 1.8, neutered 1.6, obesity prone 1.4 × RER; puppies under 4 months 3 × RER, over 4 months 2 × RER. https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutritional-requirements-of-small-animals (retrieved 2026-10-02)
- National Research Council, Nutrient Requirements of Dogs and Cats (2006), Chapter 3, Energy (the energy requirements these factors build on). https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats (retrieved 2026-10-02)
- NIST Special Publication 811, Appendix B (1 lb = 0.45359237 kg exactly). https://www.nist.gov/pml/special-publication-811 (retrieved 2026-10-02)