How Much Should I Feed My Dog? Portion Chart by Weight, Age, and Activity Level

By Wagopedia · Published November 4, 2026 · Portion math per the Merck Veterinary Manual energy-requirement method

The feeding guide printed on the bag is a starting point, not an answer: it is written for an average dog, eating that food, at an average activity level — and it can't know whether your dog is neutered, elderly, or a growing puppy. Veterinarians work the number out differently, in two steps published in the Merck Veterinary Manual: first the calories a dog burns at rest, from body weight alone, then a multiplier for life stage and activity. This guide walks through both steps, gives the full chart, and shows how to convert calories into cups of the food in your cupboard. If you would rather skip the arithmetic, our dog feeding calculator does the same math from your dog's weight, life stage, and the kcal-per-cup figure on your bag.

Step 1: Resting energy — the weight-only number

The resting energy requirement (RER) is the energy a healthy, fed dog uses at rest in a comfortable temperature. The Merck Veterinary Manual's formula is:

RER (kcal/day) = 70 × (body weight in kilograms)^0.75

The exponent is the point: metabolism does not rise in a straight line with weight, so a 100-pound dog does not need ten times the food of a 10-pound dog — it needs about five and a half times the resting calories. (For dogs between about 2 and 45 kg, the manual also allows a linear shortcut, 30 × kg + 70, which lands close to the exponential figure.) RER on its own is never the feeding amount. It is the base that step 2 scales up.

Step 2: The life-stage factor

Multiply RER by one factor — the one that matches your dog. The factors below are the Merck Veterinary Manual's daily maintenance energy requirements for dogs, with the weight-loss and inactive-dog factors as published in the Pet Nutrition Alliance (PNA) factor table:

Neutering alone moves the number meaningfully: feeding a neutered dog at the intact factor adds roughly 12% more calories every day, which is a common route to slow, unnoticed weight gain after surgery. Working and sporting dogs are the exception at the top end — the American Animal Hospital Association (AAHA) gives work factors well above the maintenance table, up to several times RER for heavy work — so a genuinely working dog is a conversation with your veterinarian, not a chart lookup.

The portion chart: adult dogs

Daily calories, computed from the formulas above and rounded to the nearest 5 kcal. The cups column assumes a food at 400 kcal per cup — check your own bag's figure and divide your dog's calorie target by it, because commercial foods vary widely in calorie density.

Worked example. A 40-pound neutered adult: RER = 70 × (18.1 kg)^0.75 ≈ 615 kcal. Times the neutered factor of 1.6 gives about 985 kcal per day. On a food labeled 400 kcal per cup, that is roughly 2½ cups a day — about 1¼ cups per meal across two meals. Change the food to one at 350 kcal per cup and the same dog needs about 2.8 cups; at 450 kcal per cup, about 2.2 cups. The calories are the diet; the cups are just packaging.

Puppies: more food per pound, more meals per day

Puppies run the same formula at growth factors. A 10-pound puppy under four months has an RER of about 220 kcal and a daily target near 650 kcal (×3.0); the same puppy at five months uses the ×2.0 factor — about 435 kcal on the way up, recalculated as weight climbs. Recalculate every couple of weeks: a growing puppy's weight, and therefore their target, changes faster than at any other life stage, and veterinary references advise weighing growing puppies weekly to confirm they are gaining steadily rather than too fast or too slowly.

Meal frequency follows age. The Merck Veterinary Manual's feeding guidance is three meals a day for puppies from weaning to about six months, and twice daily from six to twelve months; most adults do well on two meals. Young puppies also need the routine around the meals — toilet trips after eating are a housetraining fixture, as our first-week puppy checklist lays out.

Treats come out of the same budget

The chart is the whole day's calories, not the bowl's calories plus everything else. The World Small Animal Veterinary Association's (WSAVA) Global Nutrition Guidelines put the standard ceiling plainly: treats and extras should make up no more than about 10% of daily energy. For the 40-pound dog above, that is roughly 100 kcal of treats a day — a number that disappears quickly with dental chews and training rewards if nobody is counting. Either measure treats against the 10% or reduce the bowl by what the treats added; the scale cannot tell the difference.

Adjust by the dog in front of you

Every figure here is a starting estimate, and the sources say so themselves: the Merck Veterinary Manual notes an individual dog may need as much as 30% more or less energy than the formula gives, and the PNA calls its equations starting points with an even wider real-world spread. The correction mechanism is body condition. You should be able to feel your dog's ribs under a thin fat cover without pressing hard, and see a waist from above and from the side. Feed the chart amount for two to three weeks, weigh, and look: gaining when they shouldn't be, trim the portion by about 10% and recheck; losing, add 10%. Small, measured adjustments beat re-rolling the whole calculation.

Changing foods is its own variable: switch gradually over 5–7 days (longer for sensitive stomachs), per the AKC transition guidance detailed in our German Shepherd sensitive-stomach guide, and keep the calorie target constant across the switch even as the cup count changes with the new food's density.

The short version: weigh the dog, take 70 × kg^0.75, multiply by the factor that matches their life stage, and divide by the kcal per cup on your bag. Or let the feeding calculator do it — then let the ribs, the waist, and the scale correct the estimate over the following month. More feeding guides live in our Food & Nutrition section.