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How much to feed a 120 lb dog: working dog, food at 450 kcal per cup

Daily food
9.35cups a day
4,208 kcal for a 120 lb dog — working / very active, food at 450 kcal/cup
Daily calories4,208kcal
Cups per dayat 450 kcal per cup9.35cups
Twice a dayper meal4.68cups
Three times a dayper meal3.12cups
Resting energy (RER)70 × 54.4 kg^0.75 — what a dog burns doing nothing1,403kcal
Activity multipliersustained daily work, not a long walk× 3
Body weight120 lb54.4kg
Body weight
120 lb
Life stage
working dog
Food energy
450 kcal/cup

The formula, and why the bag disagrees

Resting energy is not proportional to body weight. The veterinary formula is

RER = 70 × (weight in kg)0.75

That exponent is the whole story. A 120 lb dog needs 1,403 kcal at rest, and a working figure of 4,208 kcal a day once the ×3 multiplier for working dog is applied — 9.35 cups at 450 kcal per cup.

Scaling in a straight line from a 20 lb dog would say 14.64 cups: 57% off. Feeding charts printed on bags interpolate linearly, which is why large dogs fed off the bag tend to end up heavy.

Check the calories on your bag

Dry food runs roughly 300 to 500 kcal per cup depending on brand and formula. The same "two cups" can therefore be a third more or less food than intended. The figure is on the bag, usually in small print near the guaranteed analysis, and it is the single most useful number on the packaging.

Meals

At 9.35 cups a day that is 4.68 cups twice a day, or 3.12 cups three times. Deep-chested breeds do better on smaller, more frequent meals.

Treats count, and they are the usual culprit

Treats should stay under 10% of the daily total — 421 kcal here. That is less than most people expect, and it is the common reason a carefully measured bowl still produces an overweight dog.

Where this page stops

This is arithmetic for a healthy adult dog, not medical advice. Puppies of large breeds, pregnant or nursing dogs, and any dog with kidney, heart, pancreatic or endocrine disease need a plan from a vet, and weight-loss diets should be supervised — dogs that lose weight too fast can develop serious liver problems.

Notes

  • Calories do not scale with weight. The exponent is 0.75, not 1 — a 120 lb dog needs 9.35 cups, but scaling straight up from a 20 lb dog would say 14.64 cups, 57% too much. Feeding charts printed on the bag usually interpolate in a straight line, which is why big dogs on them get overfed.
  • Check the kcal per cup on your bag. It ranges from about 300 to 500 across brands, so the same "two cups" can be a third more or less food. The figure is on the bag, usually in small print near the guaranteed analysis.
  • The ×3 multiplier is for genuine sustained work — a sled dog, a herding dog on a farm, a dog running with you daily for hours. A long walk is not it, and using this multiplier for an ordinary pet is the fastest route to an overweight dog.
  • Healthy adult dogs only. Puppies of large breeds, pregnant or nursing dogs, and any dog with kidney, heart, pancreatic or endocrine disease need a plan from a vet — the calorie figure is the least important part of those diets.
  • Treats count. They should stay under 10% of the daily total, which is 421 kcal here — less than most people think, and the usual reason a carefully measured bowl still leads to a heavy dog.

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