100 pet feeding cells — calories do not scale with body weight

Why the 0.75 power

Resting energy is taken as 70 × weight^0.75. Surface area does not grow as fast as volume, so a larger body loses less heat per kilogram. A 32 kg dog therefore eats eight times what a 2 kg dog eats, not sixteen times (16^0.75 = 8). Assume a straight proportion and you overfeed the big dog and underfeed the small one.

Why the factor is a range

The widely quoted tables disagree. A neutered adult dog is 1.6 in one and 1.4–1.6 in another, and weight loss splits on what the number even applies to — 0.8 of the current weight in one convention, 1.0 of the target weight in the other. Picking one number would be wrong for anyone holding the other table, so both ends are computed here.

Where the 30 × weight + 70 shortcut breaks

This is the shortcut most local guides use. It meets the exponential curve **twice** — around 3 kg and around 20 kg. Between those points it reads low; outside them it reads high. For a 40 kg dog it sits about 14 % above the exponential figure. Which formula was used changes the answer, so this table gives both.

Check the kcal on the bag

The gram figure is the calorie figure divided by the food’s energy density. Dry food usually runs 350–400 kcal per 100 g, so both 3.5 and 4.0 are shown. If the bag says something else, divide the daily calories by that number instead — wet food is far less dense, so the grams rise sharply.

A starting point, not a prescription

At the same weight, real needs vary by up to 30 % with activity, breed, age, and illness. Feed at this level for a couple of weeks, then weigh and reassess. Talk to a vet for any medical condition or planned weight loss — cats in particular must never drop their intake abruptly.

puppy under 4 monthsLife-stage factor 2~3

puppy 4–12 monthsLife-stage factor 1.6~2

intact adult dogLife-stage factor 1.6~1.8

neutered adult dogLife-stage factor 1.4~1.6

dog losing weightLife-stage factor 0.8~1

kitten under 4 monthsLife-stage factor 2.5~3

kitten 4–12 monthsLife-stage factor 1.8~2.5

intact adult catLife-stage factor 1.2~1.4

neutered adult catLife-stage factor 1~1.2

cat losing weightLife-stage factor 0.8~1

Linear shortcut

• 2 kg118 / 130 kcal · +10.4%
• 4 kg198 / 190 kcal · -4%
• 10 kg394 / 370 kcal · -6%
• 20 kg662 / 670 kcal · +1.2%
• 40 kg1113 / 1270 kcal · +14.1%

How to read this

• Resting energy = 70 × weight to the power 0.75. It is not proportional to weight.
• Daily calories = resting energy × life-stage factor. Tables disagree, so a range is shown.
• Grams = daily calories ÷ the kcal per gram printed on the bag.
• Feed for two weeks, then weigh again. This is a starting point.