Dog Food Calculator — How Much to Feed a Day
Grams of dog food a day from RER and MER
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Updated 2026-10-04The starting values (a 10 kg neutered adult, food at 350 kcal per 100 g, 2 meals) are an example. Replace them with your dog’s and food’s details.
0.5 to 100 kg. For a dog that needs to lose weight, use the target weight and factor from your vet.
50 to 900 kcal. Use the metabolizable energy on the bag.
1 to 6
0 to 50%. The part of the daily calories given as treats, taken off the food amount. Keeping treats under about 10% is a common rule of thumb.
About 180 g of food a day
Result
- Food per day
- about 180 g
- Per meal
- about 90 g
- Daily energy need (MER)
- 630 kcal
- Resting energy requirement (RER)
- 394 kcal
Treat the result as a starting point. Check weight and body shape every 2 to 4 weeks and adjust by around 10%.
The math with your numbers
- RER = 70 × 10^0.75 = 393.6 kcal
- MER = 1.6 × 393.6 = 629.8 kcal
- Food = 629.8 / (350 / 100) = 179.9 g; per meal 179.9 / 2 = 90 g
Needs vary a lot between dogs. For a sick, pregnant or nursing dog, or one on a prescription diet, follow your vet’s amount. Compare the result with the feeding table on the bag.
Source: the RER formula and factors (neutered adult 1.6, intact 1.8, obesity-prone 1.4, puppy under 4 months 3, over 4 months 2) follow the Merck Veterinary Manual, “Nutritional Requirements of Small Animals” (Sherry Lynn Sanderson, reviewed 2023-11; retrieved 2026-10-04). The 10% treat figure is an unsourced rule of thumb, so you set it yourself.
What it is
This calculator estimates how many calories your dog needs each day and divides that by the energy in your dog food to give grams per day. Bag feeding tables use wide weight bands, so the amount for your dog can be hard to pick. The tool uses the resting energy requirement (RER) and maintenance energy requirement (MER) formulas from veterinary nutrition and shows each step with your numbers. Add the number of meals to get grams per meal, and set a treat share if you give treats. It opens with a 10 kg neutered adult as an example.
How to use
- Enter your dog’s current weight in kg.
- Choose the life stage. Adults are split by neutering and tendency to gain weight, puppies by age around 4 months. Use Custom for any other factor.
- Enter the food’s energy per 100 g from the bag.
- Enter meals per day and, if you give treats, the treat share.
- Read the daily amount, the amount per meal and the formula.
How it works
- RER = 70 × weight (kg)^0.75 kcal per day.
- MER = factor × RER. Factors follow the Merck Veterinary Manual, “Nutritional Requirements of Small Animals”: neutered adult 1.6, intact adult 1.8, obesity-prone adult 1.4, puppy under 4 months 3, puppy 4 months or older 2.
- Calories from food = MER − MER × treat share.
- Grams per day = calories from food / (kcal per 100 g / 100); per meal = grams per day / meals.
- Results are rounded to whole grams. The same reference stresses that calculated values are only a starting point.
Examples
| Dog | Daily energy | Food energy | Food per day |
|---|---|---|---|
| 10 kg neutered adult | about 630 kcal | 350 kcal/100 g | about 180 g |
| 16 kg intact adult | 1,008 kcal | 400 kcal/100 g | 252 g |
| 5 kg puppy, 4+ months | about 468 kcal | 380 kcal/100 g | about 123 g |
| 3 kg neutered adult | about 255 kcal | 360 kcal/100 g | about 71 g |
Good to know
Activity, breed, coat and season all change real needs. Feed the calculated amount for two to four weeks, then check weight and how easily you can feel the ribs, and adjust a little at a time. Sick, pregnant or nursing dogs and dogs on prescription diets should follow their vet’s amount. Curious how old your dog is in human years? Try the pet age calculator.
FAQ
How many grams of food does my dog need?
It depends on weight, life stage and the food’s energy. A 10 kg neutered adult eating food with 350 kcal per 100 g needs about 630 kcal a day, which is about 180 g, or about 90 g per meal at two meals.
What are RER and MER?
RER is the energy used at rest, 70 × body weight in kg to the power 0.75. MER is the daily maintenance energy, RER times a life-stage factor such as 1.6 for a neutered adult or 1.8 for an intact adult.
Where do I find the food’s calories?
Look for metabolizable energy on the bag. Pick the unit the label uses (per 100 g, per kg or per cup) and enter the number as it is. With per cup the amount is shown in cups; a label cup is normally an 8 fl oz measuring cup, which may differ from your kitchen cup.
What about a dog that needs to lose weight?
Weight loss needs a target weight and factor set for the individual dog, so the list only has maintenance and growth factors. Use the target weight and factor from your vet with the Custom option.
Should treats reduce the food amount?
Yes. Enter a treat share and those calories are taken off before the food amount is calculated. Keeping treats under about 10% of daily calories is a common guideline (the WSAVA Global Nutrition Committee's advice for pet owners says the same). The default is 0%, so you choose the share.
