How much should I feed my dog?

The bag's guide is an average for a dog that does not exist. This is how to get a number for yours.

Feeding · Updated August 2026

By Eunrae Cho · Last reviewed 2026-08-20 · How we source this

The feeding guide on the bag is a starting point aimed at an average dog that does not exist. Here is how to get to a number that fits the dog in front of you.

Why calories, not cups

Two foods can look identical in a bowl and differ by 40% in energy. A dense kibble and a light one, or dry versus wet, produce completely different calorie totals at the same volume. Scoops also vary, and people fill them differently on different days.

Feeding by weight, against a calorie figure, removes all of that guesswork. A cheap kitchen scale is the single most useful piece of pet equipment most owners do not own.

Step one: resting energy requirement

RER is what your pet burns doing nothing at all — organ function, temperature, breathing. The formula used across veterinary practice is 70 multiplied by bodyweight in kilograms raised to the power of 0.75.

The 0.75 exponent matters. It means calorie needs do not scale in a straight line with size: a 40kg dog does not need twice what a 20kg dog needs, but roughly 1.7 times. This is why per-kilo rules of thumb go badly wrong at the extremes.

Step two: the multiplier

Neutering is the change people most often miss. It lowers resting metabolic rate appreciably, and portions that were correct before surgery become slightly too generous afterwards. Adjust within a few weeks rather than waiting to notice the weight.

Use ideal weight, not current weight

If your pet is overweight, calculating from current weight simply feeds them to stay overweight. Work from the weight they should be. If you do not know that figure, body condition scoring gets you close: each point above the ideal 5 on the 9-point scale represents roughly 10% excess bodyweight.

Worked examples

The arithmetic is easier to trust once you have seen it run through.

Look at the two 30kg rows. Same dog, different job, and a difference of nearly 100g a day. This is why a single number on a bag cannot be right for everyone at that weight.

Note also that the 30kg dog does not eat four times what the 5kg dog eats, despite being six times heavier. That is the 0.75 exponent at work, and it is the reason simple per-kilogram rules overfeed small dogs and underfeed large ones.

Finding the calorie figure on the packaging

Look for ME (metabolisable energy), usually printed near the analytical constituents. It appears as kcal/100g, kcal/kg, or occasionally per cup — which is the least useful, since cups vary.

If only kcal/kg is given, divide by ten to get kcal/100g. If the figure is missing entirely, contact the manufacturer or choose another brand; without it you are guessing, and guessing is what the calculator exists to replace.

Typical ranges: dry dog food 320–420 kcal/100g, wet dog food 70–120, dry cat food 350–450, wet cat food 70–110. Wet food figures look tiny because most of the weight is water — which is why switching from dry to wet means feeding a much larger weight of food for the same calories.

Puppies: feeding for growth without overfeeding

Puppies need roughly two to three times their resting energy requirement, reducing as they mature. Feed four meals a day up to about four months, three until six months, then two.

Multi-pet households

Portion control fails where pets can eat each other's food. Practical fixes: feed in separate rooms, feed at fixed times rather than leaving food down, raise the cat's bowl somewhere the dog cannot reach, and use microchip-activated feeders where one animal is on a prescription diet. Free-feeding makes accurate portioning impossible and is the most common reason a diet plan quietly fails.

Changing food safely

Slower for sensitive stomachs, and if loose stools appear, go back a step and hold there for a few days before progressing.

How to tell whether the number is right

The formula gets you a starting point; your pet's body tells you the rest. Weigh every two to four weeks, keep a written record, and check body condition by hand rather than by eye. If weight is drifting the wrong way, adjust by about 10% and hold for three to four weeks before changing again — daily fluctuation and gut fill make shorter comparisons meaningless.

Treats are food

The usual guidance is that treats should make up no more than 10% of daily calories, with the other 90% coming from complete food. In practice treats are where most quiet overfeeding happens — training sessions, table scraps, the biscuit at the door, the family member who is "just being nice".

Two practical fixes: measure the day's food into a container in the morning and take training treats from it, and agree a household rule so the dog is not being fed five times by four people.

Then adjust with your eyes and hands

Every formula is an estimate, typically accurate to within 10 to 20%. The real test is your pet's body condition over the following weeks.

• Weigh every two to four weeks and write it down.
• Run your hands over the ribs — you should feel them easily under a thin layer, without pressing.
• Look from above for a waist, and from the side for an abdominal tuck.
• Adjust in roughly 10% increments, then wait a few weeks before changing again.

When to ask a vet instead

Skip the calculator and speak to your vet if your pet is on a prescription diet, is pregnant or nursing, has diabetes, kidney, liver or thyroid disease, is losing or gaining weight without a change in feeding, or is a puppy of a giant breed — growth rate in giant breeds needs controlling for joint development, and overfeeding causes real harm.

Common questions