There is no single answer to “how much should I feed my dog”, because the right portion depends on three things at once: the dog's energy requirement, the calorie density of the specific food, and how much comes in as treats. Get those three right and the portion falls out of the arithmetic.

The calculator above does that arithmetic for the food in your cupboard. This guide gives the reference charts, explains why packet guidelines are consistently generous, and covers wet, dry, raw and mixed feeding, puppies, and what it all costs at British prices.

How much food should I feed my dog?

Work in two steps, always in this order.

A 20 kg neutered adult needs about 1,060 kcal a day. On a dry food declaring 360 kcal per 100 g, that is 294 g a day — two meals of roughly 147 g. On a richer 420 kcal food it is 252 g. On a wet food at 85 kcal per 100 g it is 1,247 g, or about three 400 g tins.

The energy density is the part owners skip. Two bags of adult dry food sitting next to each other on a British supermarket shelf can differ by 30 per cent in calories per gram. Feeding the same weight of both will make a dog thin on one and fat on the other. The number is on the packaging as “metabolisable energy”, usually in kcal per 100 g or per kilogram; if it is not, the manufacturer's website will list it.

Why the back of the bag overfeeds

Packet feeding guides are not wrong so much as built for a different dog. They are generally calculated for an entire, active adult — a dog with roughly a 1.8 to 2.0 multiplier — while the typical British pet dog is neutered, walked for an hour a day and sits at 1.6. That difference alone is 15 to 25 per cent.

They also assume no treats. Add a daily dental chew and a handful of training rewards and the gap widens further. And they are given in broad weight bands — “10–20 kg: 200–300 g” — which leaves a 50 per cent range for the owner to guess within.

None of this means ignoring the bag. Use it as a sanity check: if your calculated figure is wildly outside the packet range, re-check your arithmetic and the declared energy value before trusting it.

Dry food chart by weight

The table shows grams per day for a neutered adult dog at maintenance, across the three common kibble densities. Split each figure across two meals.

Adjust from there: an entire dog needs about 12 per cent more than these figures, a genuinely active dog 25 to 55 per cent more, and an elderly or inactive dog 15 to 25 per cent less.

Wet food and mixed feeding

Wet food is mostly water — typically 75 to 82 per cent — so it takes roughly four times the weight of kibble to deliver the same calories. That is why a dog switched from dry to wet appears to be eating enormous amounts, and why a dog switched the other way looks underfed.

Mixed feeding is where most portion errors happen, because owners add wet on top of a full dry ration rather than swapping part of it out. The rule is to decide the split by calories, not by volume.

Worked example, a 20 kg dog on 1,059 kcal with a 50/50 split:

• 530 kcal from dry at 360 kcal/100 g = 147 g kibble
• 530 kcal from wet at 85 kcal/100 g = 623 g wet, about one and a half 400 g tins

A common shortcut — half a tin as a “topper” over the full dry portion — adds roughly 170 kcal, or 16 per cent of that dog's daily allowance, every single day.

Puppy portions and meal frequency

Puppies need more calories per kilo than adults and smaller, more frequent meals because their stomachs are small and their blood sugar drops quickly.

Large and giant-breed puppies need food formulated for them, with controlled calcium and a moderate energy density. Feeding a standard rich puppy food, or supplementing calcium, accelerates growth in exactly the way that damages developing joints.

Raw feeding and the 2–3 per cent rule

Raw feeders generally work from body weight rather than calories: 2 to 3 per cent of ideal adult body weight per day, split across two meals.

Puppies on raw are usually fed 5 to 6 per cent of current weight, tapering towards the adult percentage as growth slows. The percentage rule is approximate because fat content varies enormously between raw recipes — a fatty mince can carry twice the calories of a lean one at the same weight. If a raw-fed dog is gaining or losing, adjust by 10 per cent rather than assuming the percentage is wrong.

Two practical points for UK raw feeders: buy from a supplier operating under DEFRA approval for raw pet food, and handle it with the same hygiene you would raw chicken for yourself — separate board, hot wash, and no licking of faces immediately after a meal in households with babies, elderly or immunosuppressed people.

Cups, scoops and why they fail

American feeding guides are written in cups, and many bags sold in the UK carry a scoop. Both are unreliable for three reasons: a “cup” is a volume, kibble pieces vary in size and density, and no two people fill a scoop the same way.

The spread between the top and bottom row is nearly double. A cup is a useful unit once you have weighed your food once: fill the scoop, weigh it, and write the gram figure on the bin with a marker. After that the scoop is fine.

Splitting the day: meals and timing

Two meals a day suits most adult dogs. It spreads hunger, keeps energy steady, and in large deep-chested breeds — Great Danes, Weimaraners, Setters, Standard Poodles — splitting the ration and avoiding a single large meal is one of the measures associated with lower bloat risk, along with avoiding vigorous exercise for an hour either side of eating.

• Once a day works for some adult dogs and appears harmless in most, but leaves a long hungry stretch and is not appropriate for puppies, toy breeds or diabetic dogs.
• Three or four meals suit puppies, toy breeds prone to low blood sugar, and dogs recovering from illness.
• Fixed times help with house training and let you spot a missed meal, which is often the first sign a dog is unwell.
• Diabetic dogs must be fed on a schedule tied to their insulin; never change the pattern without veterinary advice.

Free feeding — leaving a full bowl down all day — is the single strongest predictor of an overweight dog, and it removes your ability to notice a lost appetite.

Changing food without upsetting the gut

Transition over seven to ten days. A faster change is the usual cause of the loose stools that get blamed on the new food itself.

Mix by calories, not by volume, if the two foods differ in density — otherwise the “50/50” stage quietly changes the total calories as well as the ingredients. Sensitive dogs, and any dog moving between very different formats such as dry to raw, may need a fortnight.

What feeding a dog costs in the UK

Portion size is also the main lever on food spend. Typical 2026 UK costs, feeding a correctly calculated ration:

Two things reduce the bill more than switching brand. Feeding the correct portion rather than a generous one typically cuts 15 to 25 per cent off consumption. And buying the largest bag the dog will get through within about six weeks of opening usually cuts the per-kilo price by a fifth — beyond that, fats in the kibble begin to oxidise and palatability drops.

Frequently asked questions