Tool
Dog food calculator (calories and cups per day)
Calculate nowQuick answer
A dog's daily food starts with resting energy: RER = 70 × (body weight in kg)^0.75, in kcal per day. That is multiplied by a maintenance factor from the Merck Veterinary Manual: 1.6 for a spayed or neutered adult, 1.8 for an intact adult, 1.4 for a dog prone to weight gain, 3 for puppies under 4 months and 2 for puppies over 4 months. Divide the result by the kcal/kg on the label to get grams. Treat it as a starting point and adjust by body condition.
Guide · $9The Dog and Cat Food GuideHow the math works
Step 1, resting energy. The calculator converts pounds to kilograms and applies the formula from the Merck Veterinary Manual:
RER = 70 × (body weight in kg)0.75
The 0.75 exponent matters: a 90 lb dog does not need twice what a 45 lb dog needs.
Step 2, maintenance factor.
| Situation | Factor |
|---|---|
| Puppy under 4 months | 3 × RER |
| Puppy over 4 months | 2 × RER |
| Adult, intact | 1.8 × RER |
| Adult, spayed or neutered | 1.6 × RER |
| Adult, prone to weight gain | 1.4 × RER |
Step 3, calories to food. Daily kcal ÷ kcal/kg on the label × 1,000 = grams per day. Without the label number the tool shows calories only, because dry and canned foods differ several times over in energy density.
Limits
The numbers rest on the nutrient profiles of the National Research Council (Nutrient Requirements of Dogs and Cats, 2006) as summarized by Merck. Individual dogs vary, so the real check is body condition: the WSAVA treats nutritional assessment as a routine part of every exam. Weigh and score your dog every few weeks and adjust. For weight loss, pregnancy, kidney, heart or diabetic patients, the amount is part of treatment and belongs to your veterinarian. See also the dog ideal weight calculator.
Frequently asked questions
Why does the feeding chart on the bag give a different number?
The chart is written for an average dog in that weight band. It does not know whether yours is neutered, a couch potato or a working dog. The RER method starts from your dog's real weight and situation, so it often comes out lower for neutered adults.
Does it work for pregnant or nursing dogs?
No. Late pregnancy and lactation raise energy needs by a large and variable amount. Your veterinarian should set the amount and follow the weight closely.
My dog needs to lose weight. Should I just feed less?
Not on your own. The Merck Veterinary Manual suggests starting weight loss at about 60% of the maintenance energy, but that needs a target weight set by your vet and regular rechecks. Use the ideal weight calculator first to see how much extra weight there is.
Where do I find kcal/kg on a US label?
Pet food labels list calorie content as kcal per kilogram, usually next to kcal per cup. Use the per kilogram number here; the result is shown in grams and ounces.
Sources
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