Pet Food Portion Calculator
Feed the pet in front of you — weigh the food and adjust to body condition.
Work out how much to feed your dog or cat each day — grams of food and grams per meal — from bodyweight, life stage or goal and your food's energy. It uses the vet-standard energy method (RER then MER), so the number is tailored to your pet, not just the back of the bag.
Estimates from bodyweight, life stage and typical food energy — a planning guide only. Always follow your vet's advice and adjust to body condition.
How the daily amount is worked out
Energy first, then grams
Vets don't feed by weight, they feed by energy. First comes the Resting Energy Requirement — the calories an animal burns just existing: RER = 70 × bodyweight(kg)0.75 kcal/day. That resting figure is then scaled up by a life-stage factor to give the Maintenance (Daily) Energy Requirement, MER = RER × factor. Typical factors are about ×1.6 for a neutered adult dog and ×1.2 for a neutered adult cat, rising to ×2–3 for a growing puppy or kitten and higher again for hard-working dogs; for weight loss the RER is taken on the target weight and multiplied by about ×1.0 (dog) or ×0.8 (cat). Finally, calories become food: grams/day = MER × 100 ÷ the food's energy density (kcal/100 g). This is the WSAVA/AAHA global veterinary standard — the equation isn't country-specific, but the factor, your food's energy and the ideal weight all vary, so they're inputs.
Worked example
A neutered 20 kg dog (about 44 lb): RER = 70 × 200.75 ≈ 662 kcal, then MER = 662 × 1.6 ≈ 1,059 kcal/day. On a typical dry food at 375 kcal/100 g that's 1,059 × 100 ÷ 375 ≈ 282 g of food a day — about 141 g per meal split over two meals. Switch to a wet food at ~90 kcal/100 g and the same dog needs roughly 1,177 g, because wet food is mostly water.
Kilograms in, grams out — on purpose
The inputs are metric and so is the answer, and that's deliberate rather than an oversight. The veterinary equation is defined on kilograms, and grams are the unit vets actually dose food in — so working in kg and g keeps the math honest instead of bouncing through two conversions. If your bathroom or pet scale reads pounds, just divide by 2.2: 44 lb = 20 kg, 11 lb = 5 kg, 66 lb = 30 kg, 22 lb = 10 kg, 9 lb = 4 kg. And on the output side, a cheap kitchen scale set to grams is the single biggest accuracy upgrade you can make to your pet's bowl — more on why below.
This is an estimate, not a prescription. Individual pets vary by breed, metabolism, health and neuter status. Weigh the food, watch the body condition score, and adjust every couple of weeks. Your vet's advice always overrides this tool — especially for puppies, kittens, pregnancy, illness or a weight-loss plan.
Why life stage changes the amount so much
The same bodyweight can need very different amounts of food depending on age, neuter status and how active the animal is. These are the typical MER factors applied to Resting Energy Requirement:
- Inactive / senior — ~×1.2–1.4. Older, quieter pets burn less; it's easy to keep feeding "adult" amounts and watch the weight creep on.
- Neutered adult — ~×1.6 dog, ×1.2 cat. Neutering lowers energy needs, so a spayed or neutered pet needs noticeably less than an intact one of the same weight.
- Intact adult — ~×1.8 dog, ×1.4 cat. Intact animals run a little hotter.
- Active / working — ~×2–5 dog. A weekend agility dog sits near the bottom of that range; a full-time working or sled dog near the top.
- Growth (under 4 months) — ~×3, then ~×2 (4–12 months). Puppies and kittens are building a body and need far more energy per kilo than adults.
- Weight loss — RER on the target weight × ~1.0 dog / ×0.8 cat. Weight gain for an underweight pet nudges the factor the other way.
The same math, three very different bowls
A 10 kg puppy (about 22 lb) aged 4–12 months uses a ×2.0 growth factor: RER 394 kcal × 2.0 = 787 kcal/day, or about 197 g of a 400 kcal/100 g puppy food, split across three meals of roughly 66 g. A 30 kg working dog (about 66 lb) at ×2.5 needs around 2,243 kcal — roughly 598 g of 375 kcal/100 g dry food, more than twice the neutered 20 kg dog's bowl. And a 4 kg small-breed dog (about 9 lb) at ×1.6 needs only about 317 kcal, or roughly 84 g a day — but note that's more per kilo than the big dog gets, because the 0.75 exponent means small animals burn energy faster for their size. You can't just scale a large dog's portion down by weight; run the equation.
Pick the row that matches your pet honestly — over-estimating activity is the most common way pets are quietly overfed. If your vet has given you a specific multiplier, enter it in the Detailed level to override the goal.
Food energy, reading the label and weighing portions
Dry vs wet — it's all about water
A typical dry food holds about 375 kcal per 100 g; a typical wet food only about 90 kcal per 100 g, because it's roughly three-quarters water. To reach the same daily calories your pet needs about four times the weight of wet food — a 5 kg cat on 281 kcal a day eats about 75 g of dry food but roughly 312 g of wet. The energy is identical; only the density changed. Always compare foods on calories, not grams.
Reading a US pet-food label
US pet food carries an AAFCO calorie content statement. It gives metabolizable energy as kcal per kilogram, and usually kcal per cup alongside it. This calculator wants kcal per 100 g, so divide the kcal/kg figure by 10 — a food listed at 3,750 kcal/kg is 375 kcal/100 g. Enter your own food's number for the most accurate result: this single figure, not the brand or the price, is what sets the portion, and it ranges widely — roughly 300–450 kcal/100 g for dry and 70–130 for wet, with "light" and performance formulas at opposite ends.
Weigh in grams, don't scoop cups
Here's where American feeding habits quietly go wrong. A cup is a measure of volume, not energy — and the weight of a cupful shifts with kibble size, shape and density, so the very same scoop holds meaningfully different amounts of two different foods. That's why the label prints kcal/kg as well as kcal/cup, and why the kcal/kg figure is the one to trust. Studies of home portioning have found cup measures off by 20–50% — enough to erase a diet, or to add a slow pound a year. A kitchen scale in grams costs less than a bag of food and gives the same portion every time, for every food.
If you'd still rather think in cups — and most of us do — you can have both: weigh one level scoop of your food once, enter that gram weight in the Detailed level's scoop field, and the results will show approximate cups per day next to the grams. Then keep treats under about 10% of daily calories — chews and training treats count, and they add up fast. Let the body condition score, not the bowl, be the final word: you should feel the ribs easily with a light cover, and see a waist from above.
❓ Frequently asked Frequently asked questions
How much should I feed my dog?
It depends on weight, life stage and activity, not just a number on the bag. Vets use the animal's Resting Energy Requirement — RER = 70 × bodyweight(kg)^0.75 kcal/day — then multiply by a life-stage factor: about 1.6 for a neutered adult, 1.8 for an intact adult, up to 2.0 or more for a working dog, and 2–3 for a growing puppy. A neutered 20 kg dog (about 44 lb) needs roughly 1,059 kcal a day, which is about 282 g of a typical dry food at 375 kcal/100 g. Split it across two meals — roughly 141 g each — and adjust up or down every couple of weeks to keep a lean body condition.
How much should I feed my cat?
Cats need far fewer calories than their size suggests. Using RER = 70 × weight^0.75 and a factor of about 1.2 for a neutered indoor adult, a 5 kg cat (about 11 lb) needs roughly 281 kcal a day — that's an RER of 234 kcal multiplied by 1.2. On a dry food at 375 kcal/100 g that's only about 75 g — a small amount that's easy to overfeed. Growing kittens and pregnant or nursing queens need much more (a factor of 2–3). Weigh the food rather than free-pouring, and let body condition, not the bowl, guide the amount.
Why is the wet-food portion so much bigger than dry?
Because wet food is mostly water. A typical dry food packs about 375 kcal per 100 g, while wet food is only around 90 kcal per 100 g — roughly a quarter as dense. To hit the same daily calories your pet therefore needs about four times the weight of wet food: the 5 kg cat that eats 75 g of dry food a day needs about 312 g of wet food for the identical 281 kcal. The animal isn't eating more energy; it's eating more water. That's why the gram figure jumps when you switch the food type — always compare foods on calories, not grams.
How do I read the calories on a US pet-food label?
US pet-food labels carry an AAFCO calorie content statement. It gives metabolizable energy as kcal per kilogram, and usually kcal per cup alongside it. This calculator asks for kcal per 100 g, so divide the kcal/kg figure by 10 — a food listed at 3,750 kcal/kg is 375 kcal/100 g. Prefer the kcal/kg number over the kcal/cup one: a cup measures volume, and the weight of a cupful shifts with kibble size and shape, so weighing in grams on a kitchen scale is far more accurate than scooping. Once you have kcal/100 g, grams per day = daily calories × 100 ÷ energy density.
How do I feed my pet for weight loss?
Feed to the target (ideal) weight, not the current one, and go gently. A common vet approach bases the RER on the ideal weight and uses a factor of about 1.0 for dogs and 0.8 for cats, then reduces further only under veterinary supervision. A cat that weighs 5 kg but should be 4 kg works out at about 158 kcal a day — roughly 42 g of dry food — while a dog coming down from 25 kg to a 22 kg target lands near 190 g. Keep treats under 10% of daily calories, weigh the food, and aim for slow loss — roughly 1–2% of bodyweight a week — with regular weigh-ins. Crash dieting is dangerous for cats in particular (risk of hepatic lipidosis), so always involve your vet in a weight-loss plan.
Where these figures come from
The method here is the mainstream veterinary-nutrition standard, not a country-specific rule. The energy equation and life-stage factors follow the WSAVA Global Nutrition Guidelines and AAHA feeding guidance; the food energy defaults are typical values you can replace with your own product's label figure.
- Resting Energy Requirement — RER = 70 × bodyweight(kg)^0.75 kcal/day (the standard allometric formula).
- Life-stage (MER) factors — neutered adult ~×1.6 (dog) / ×1.2 (cat); intact ~×1.8 / ×1.4; active/working ~×2–5; growth ~×3 then ~×2; weight loss RER on target weight ×~1.0 (dog) / ×0.8 (cat).
- Food energy density — typical dry food ~375 kcal/100 g, typical wet food ~90 kcal/100 g. US labels carry an AAFCO calorie content statement giving metabolizable energy as kcal/kg (÷10 for kcal/100 g), usually with kcal per cup alongside.
- Treats — kept to ≤10% of daily calories, in line with standard veterinary advice.
Last checked: July 2026. This is a planning estimate, not veterinary advice. Individual needs vary with breed, health, metabolism and neuter status — weigh the food, monitor body condition, and follow your own vet's recommendation, especially for puppies, kittens, pregnancy, illness or weight loss.
Select the question that matches where you are right now.
The headline number is the estimated amount of food to feed per day — grams, plus grams per meal — to meet your pet's daily calories (MER) on the food you chose. The breakdown shows the resting and daily calories behind it and how much each meal works out to.
Use it as a starting point, weigh that amount, and split it across the meals you feed. Then check body condition every couple of weeks and nudge the amount up or down — the scale and the ribs are the real feedback, not the bowl.
It's not veterinary advice or a fixed prescription. It doesn't account for illness, pregnancy, medications or an individual dog or cat's metabolism. For puppies, kittens, weight loss or any medical condition, feed to your vet's plan.
Feeding by energy is how vets do it, because two foods that fill the same cup can differ hugely in calories. Enter your food's real kcal/100 g and the grams figure adjusts — a richer food means a smaller bowl.
Four things move the daily amount the most: bodyweight, life stage or goal, how active the pet is, and the food's energy density.
RER scales with weight to the power 0.75, and the life-stage factor can nearly double the result — a growing puppy needs far more per kilo than a neutered senior of the same weight.
Dry (~375 kcal/100 g) versus wet (~90) changes the grams roughly four-fold for the same calories. Always feed to your own food's AAFCO figure, not a generic gram amount.
Honest activity matters — over-rating it is the classic overfeeding trap. Treats should stay under ~10% of daily calories, and a weight-loss goal feeds to the target weight, not today's weight, so the amount deliberately comes down.
A few habits keep the portion honest and your pet in good shape.
Use a kitchen scale in grams — cup measures can be out by 20–50%, because a cup of food weighs whatever the kibble's size and shape make it weigh. Weigh the daily amount once and mark the level on your scoop so the whole household feeds the same.
You should feel the ribs with a light cover and see a waist from above. If not, adjust by ~10% and re-check in two weeks — small, steady changes beat big swings.
Chews, training treats and table scraps are calories too. Keep them under 10% of the daily total and take that energy off the meals so the sums still add up.
Pet food is one line in the household budget. Model the wider cost of a pet and how it fits your monthly outgoings.