Dog Feeding Calculator: How Much Food Your Dog Needs and What It Costs

Work out how many calories your dog needs each day, how many grams or cups of food that is, and what it costs per day. The calculator uses the resting energy requirement formula from the National Research Council.

How the Dog Feeding Calculator works

The calculator uses the resting energy requirement, or RER, from the National Research Council. The formula is RER equals 70 times weight in kg to the power 0.75. That gives the calories a dog needs at rest. It then multiplies RER by a factor for life stage and activity. A puppy under 4 months uses a factor of 3.0, a puppy of 4 to 12 months uses 2.0, a neutered adult uses 1.6, an intact adult uses 1.8, and a less active senior uses 1.2. Low activity multiplies the factor by 0.85, and high activity multiplies it by 1.25. The result is daily calories. The calculator then divides daily calories by calories per kg of food, and multiplies by 1,000, to give grams per day. It divides grams by 110 to give cups, because a typical cup of dry food weighs about 110 grams, and check your food label, because cup weight varies by brand. It multiplies grams per day by price per kg divided by 1,000 to give cost per day.

These are starting points, not exact prescriptions. Weigh your dog every month, and adjust the food by 10 percent if your dog gains or loses weight. A dog that is gaining weight needs less food. A dog that is losing weight, and is otherwise healthy, needs more food. Ask your vet if you are unsure, especially for a puppy, a pregnant dog, a working dog or a dog with a health condition.

Worked example: a 20 kg adult dog

Take a healthy adult neutered dog that weighs 20 kg, with normal activity. RER is 70 times 20 to the power 0.75, which is about 662 calories. The factor for a neutered adult with normal activity is 1.6, so daily calories are about 1,059. If the food has 3,600 calories per kg, the dog needs about 294 grams a day, or about 2.7 cups. If the food costs $5 per kg, the cost per day is about $1.47, and the cost per month is about $44. If the same dog is very active, the factor rises to 2.0, daily calories rise to about 1,324, food rises to about 368 grams a day, and cost rises to about $1.84 a day. If the dog is a senior with low activity, the factor falls to about 1.0, daily calories fall to about 662, and food falls to about 184 grams a day.

How much food does a dog need per day by size

A small dog of 5 to 10 kg needs about 300 to 550 calories a day, which is about 80 to 150 grams of dry food. A medium dog of 15 to 25 kg needs about 800 to 1,300 calories a day, which is about 220 to 360 grams. A large dog of 30 to 45 kg needs about 1,400 to 2,100 calories a day, which is about 390 to 580 grams. A giant dog of 50 kg and over needs about 2,200 to 3,000 calories a day, which is about 610 to 830 grams. Puppies need more per kg than adults, and senior dogs need less. Use the calculator above for your dog's exact weight, life stage and activity, and read our dog food cost per day guide for cost per day by size and food type.

US and UK feeding guidance

The formula in this calculator is from the National Research Council, and it is used by vets and by the American Animal Hospital Association and the World Small Animal Veterinary Association. The same formula is used in the US and the UK. Food labels in both countries show calories per kg, and feeding guides on the bag give a starting amount by weight. Use the bag guide as a starting point, then adjust for your dog. In the UK, ask your vet or use the PDSA feeding guidance if you are unsure. Do not feed a dog by the maximum on the bag, because most dogs will gain weight if they eat the maximum every day.

Frequently asked questions

How many calories does my dog need per day?

It depends on weight, age and activity. A 10 kg dog needs about 400 to 600 calories a day. A 20 kg dog needs about 1,000 to 1,100 calories a day. A 30 kg dog needs about 1,400 to 1,600 calories a day. Use the calculator above for your dog.

How many cups of food should I feed my dog?

A cup of dry food weighs about 110 grams, but it varies by brand, so check your food label. A 20 kg dog needs about 2.7 cups a day of a typical dry food. Weigh the food with kitchen scales for the most accurate amount.

Should I feed my puppy more than an adult dog?

Yes, per kg of body weight. Puppies need about 2 to 3 times the resting energy need, because they are growing. Feed puppy food, not adult food, and ask your vet for the right amount for your puppy's age and expected adult size.

What is RER in dog feeding?

RER is resting energy requirement, the calories a dog needs at rest in a day. The formula is 70 times weight in kg to the power 0.75. Daily calories are RER times a factor for life stage and activity. The formula comes from the National Research Council.

Related guides and calculators

Sources and how we priced this

Prices in this guide are ranges, not single facts, because published sources disagree. We used the American Pet Products Association 2025 and 2026 industry figures, Rover 2026 cost of dog ownership reports, the PDSA PAW Report and PDSA cost guides for the UK, the American Animal Hospital Association and the National Research Council feeding guidance, and published insurer and vet price lists in the US and the UK. All prices were checked in Nov 2026 and are shown in US dollars unless a UK section says pounds. Where a source gave one number, we widened it into a range to reflect size, breed and location.