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Dog Food Amount Calculator

Find out how many cups of dry food or cans of wet food your dog needs a day, based on its weight, age and the food label.

Level: Grades 9–10

Printable worksheet

Dog Food Amount Calculator

Know the answer you need? Pick an input to work backward.

Inputs

Current weight, or the target weight your vet suggests if the goal is weight loss.

Food

Printed on the bag as kcal/cup (calorie content).

Treats and chews count toward the day's calories, so they are taken off the food.

Result

Dry food per day

1.67 cups

Start with about 1.67 cups a day (about 649 kcal including treats), then adjust with your veterinarian as you watch your dog's weight.

Dry food per meal
0.83 cups
Daily calories (starting point)
649 kcal/day
Life stage range
606–692 kcal/dayAdult, spayed or neutered
Treat allowance
65 kcal/day
Resting energy requirement (RER)
433 kcal/day

See the step-by-step solution ↓

Step-by-step solution

  1. Turn pounds into kilograms, the unit the calorie formula uses (1 lb = 0.45359237 kg)

    25 lb×0.45359237=11.3398 kg

  2. Find the calories your dog burns at rest (RER): 70 times its weight in kg to the power 0.75

    70×11.33980.75=432.6 kcal/day

  3. Start from the middle of the 1.4–1.6 life stage factor range, which allows for growth and activity

    1.4+1.62=1.5

  4. Multiply the resting calories by that factor to get the day's calories

    432.6×1.5=648.8 kcal/day

  5. Take off the 10% of calories that treats will cover, so the day's total stays the same

    648.8×1−0.1=584 kcal

  6. Divide by the calories in one cup to see how many cups of dry food that is

    584350=1.6685 cups/day

  7. Share it out across 2 meals

    1.66852=0.8342 cups

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find out how much to feed your dog each day, in cups of dry food or cans of wet food. The feeding chart on a bag covers every dog of a given weight with one line. So it can't allow for whether your dog is spayed or neutered, still growing, or mostly asleep on the sofa. A better starting point is your dog's daily calorie need, divided by the calories in the food you actually buy. This calculator does both steps. It gives cups of dry food, cans of wet food, or a mix of the two, per day and per meal.

The calorie estimate starts with the resting energy requirement (RER), the calories your dog burns just resting. That's 70 × (body weight in kg)^0.75. The "^0.75" means "to the power 0.75". It's then multiplied by a life stage factor from the 2021 AAHA Nutrition and Weight Management Guidelines for Dogs and Cats. Most factors are ranges, so the calculator starts from the middle and shows the whole range too. Treat calories come off first, so the food amount leaves room for them. It's a starting point to check with your veterinarian, not a prescription.

Where it's used

Why this math matters outside the classroom:

  • Switching foods. An owner moving from a 350 to a 450 kcal/cup food cuts 1.67 cups a day to 584 ÷ 450 ≈ 1.30 cups.
  • Puppy meals. A 20 kg puppy over 4 months needs about 2 × 70 × 20^0.75 ≈ 1,324 kcal a day, split into several meals.
  • Weight loss plan. For a 10 kg target weight, 70 × 10^0.75 ≈ 394 kcal a day is about 0.98 cups of a 400 kcal/cup food.
  • Treat budgets. A dog sitter allows 10% of a 650 kcal day, about 65 kcal, for training treats and cuts the meals to match.
  • Power laws. Students compare 40^0.75 ÷ 10^0.75 = 4^0.75 ≈ 2.83 to see why a dog 4 times heavier needs under 3 times the food.

How to use it

  1. Enter your dog's weight in pounds or kilograms, and choose the life stage that fits best.
  2. Choose dry food, wet food or both. Enter the calories per cup or per can from the label.
  3. Set the share of calories you give as treats, and the number of meals a day.
  4. Feed the amount shown and weigh your dog every few weeks. Adjust with your veterinarian's help.

What the inputs mean

Dog's weight
Current weight, or the target weight your vet suggests if the goal is weight loss.
Life stage and activity
Spayed and neutered adults usually need less than intact dogs. Puppies under 4 months need about three times their RER. For weight loss, enter the target weight your veterinarian suggests. Pregnancy, nursing and heavy work need advice for your own dog, so they aren't included.
Dry food calories per cup
US pet food labels list calories (kcal) per kilogram, and usually per cup or per can too. Foods differ a lot, from under 300 to over 500 kcal per cup. That's why two foods can need very different amounts.
Wet food calories per can
Printed on the can as kcal/can. Small cans often hold about half as much as large ones.
Calories from treats
Many veterinarians suggest keeping treats to about 10% of daily calories. Whatever you choose, the calculator takes it off the food, so the total stays the same. Set it to 0 if you don't give treats.

Formula and method

RER (kcal/day) = 70 × (weight in kg)^0.75;  1 lb = 0.45359237 kg
daily calories = RER × middle of the life stage factor range
food calories = daily calories × (1 − treat % ÷ 100)
cups per day = dry food calories ÷ kcal per cup;  cans per day = wet food calories ÷ kcal per can
per meal = daily amount ÷ meals per day

kcal is the calorie unit on pet food labels. The 0.75 power shows that energy use grows more slowly than body weight. A 40 kg dog weighs four times as much as a 10 kg dog, but needs only about 2.8 times the calories. The life stage factor scales the resting figure up for growth and activity. It uses the AAHA ranges, for example 1.4–1.6 for a spayed or neutered adult.

Dividing the food's share of the calories by the kcal per cup or per can on the label turns energy into an amount you can measure. When you feed both kinds, the wet food share is set first, and dry food makes up the rest.

Worked example

A 25 lb spayed adult dog eats dry food with 350 kcal per cup, gets 10% of its calories from treats, and has two meals a day.

  1. Weight in kg: 25 × 0.45359237 = 11.34 kg.
  2. RER: 70 × 11.34^0.75 = 432.6 kcal/day.
  3. Factor range 1.4–1.6, so start at 1.5: 432.6 × 1.5 = 648.8 kcal/day.
  4. Less 10% for treats: 648.8 × 0.9 = 584.0 kcal from food.
  5. Cups per day: 584.0 ÷ 350 = 1.67 cups, or about 0.83 cups per meal.

Result: Start with about 1.67 cups of food a day (0.83 cups at each of two meals), plus about 65 kcal of treats.

Understanding the result

Weigh your dog every two to four weeks. If an adult dog is gaining weight it doesn't need, feed toward the low end of the range. If it's losing weight, move toward the high end. Your veterinarian can also score body condition (how lean or heavy your dog looks and feels), which matters more than the number on the scale.

Measure with a standard 8 fl oz measuring cup and level it off. A heaped scoop can hold quite a bit more than a cup, and that adds up over months.

Assumptions and limitations

  • The weight is your dog's healthy current weight, or the target weight for weight loss.
  • Your dog is healthy and the AAHA factors fit it. The middle of each range is the starting point.
  • The calories are as printed on the label.
  • It's an estimate, not veterinary advice. Every dog is different. A dog with a medical condition or on a prescription diet should be fed as its veterinarian directs.
  • It doesn't cover pregnancy, nursing, heavy work or getting over an illness.
  • Puppies grow quickly, so work it out again as their weight changes, and use a food made for growth.

Frequently asked questions

How many cups of food should I feed my dog?

Divide your dog's daily calories by the kcal per cup on the food label. A 25 lb spayed adult needs about 650 kcal a day. With 10% from treats and a 350 kcal/cup food, that's about 1.67 cups a day.

How much should a 40 lb dog eat?

A 40 lb (18.1 kg) spayed or neutered adult has an RER of about 615 kcal. At the middle of its range, it needs roughly 923 kcal a day. With 10% from treats and a 350 kcal/cup food, that's about 2.37 cups a day. More active or intact dogs need more.

How do I mix wet and dry food?

Choose Both, then set the share of food calories from wet food. Say a quarter of the calories come from cans. The calculator gives the cans for that quarter and the cups of dry food for the rest, so the total stays the same.

Why is this different from the chart on the bag?

Bag charts cover a wide range of dogs at each weight and are often generous. This estimate allows for life stage and treats, and it uses your food's own calories. Your dog's weight over the next few weeks is the best guide to which is right.

Sources

How this calculator is checked

Method: RER = 70 × BW(kg)^0.75 and daily energy = RER × life stage factor (midpoint of the range), with canine factor ranges from the AAHA 2021 Nutrition and Weight Management Guidelines; amounts from label kcal per cup or can. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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