Pet Food Portion Calculator
How much to feed a dog or cat each day, in grams and per meal, from its weight, life stage and the food's energy density — using the resting energy equation vets use.
Resting energy requirement (RER) = 70 × weight^0.
| Resting need (RER) | 662 |
|---|---|
| Daily need (MER) | 1,059 |
How the pet food portion calculator works
Resting energy requirement (RER) = 70 × weight^0.75 kcal a day. Multiply by the life-stage factor — a neutered adult dog 1.6, an active dog 2.5, a growing puppy up to 3.0; cats run lower — for the daily energy need (MER). Take off any treat allowance, then divide by the food's energy density (about 375 kcal per 100 g for dry food, 90 for wet) to get grams a day, and by the meals to get grams a meal. For weight loss, feed to the target weight.
Formula: RER = 70 × kg^0.75 · MER = RER × factor · grams/day = MER × (1 − treats%) × 100 ÷ kcal per 100 g · per meal = ÷ meals
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.
Life-stage & activity factorsWhy 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, labels & weighingFood 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
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.
- Further guidance — ASPCA — pet care guidance.
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.
Understanding your resultSelect 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.
What to do with itUse 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.
What it is notIt'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.
Why calories, not cupsFeeding 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.
Weight & life stageRER 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.
Food energyDry (~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.
Activity, treats & goalHonest 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.
Weigh, don't scoopUse 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.
Score the body, not the bowlYou 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.
Count the treatsChews, 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.
How old is your dog, really?Translate their age into human years by size.
Dog age calculator → The whole householdSee how food and pet care fit your monthly running costs.
Cost of living → A buffer for the vet billBuild a rainy-day fund for the unexpected vet visit.
Emergency fund → Related calculators 🐕Dog AgeDog years to human years 🐈Cat AgeCat years to human years 🧾Cost of LivingHousehold running costs 🛟Emergency FundRainy-day buffer 👶Baby CostCost of a new arrival 📊Net WorthYour full picture You might also be interested in 🐕Dog AgeIn human years 🐈Cat AgeIn human years 🧾Cost of LivingBudget the whole home 📒Budget PlannerPlan the monthly spend 🛟Emergency FundBuild a buffer 🍎CalorieYour own daily energy Rate this calculatorQuick answers
How much to feed a 20 kg adult dog ≈ 282 g/day (dry food)
A neutered 20 kg adult dog needs about 1,059 kcal a day (RER 662 kcal × 1.6). On a typical premium dry food at 375 kcal/100 g that's about 282 g a day — roughly 141 g per meal across two meals. Always check YOUR bag's energy figure (AU labels show kcal/kg — divide by 10 for kcal/100 g) and adjust to body condition.
| Energy need (MER) | ≈1,059 kcal |
|---|---|
| Dry food/day | ≈282 g |
| Per meal | ≈141 g × 2 |
- Read the bag kcal/kg ÷ 10
- Weigh, don't scoop More accurate
How much to feed a 5 kg cat ≈ 75 g/day (dry food)
A neutered 5 kg cat needs about 281 kcal a day (RER 234 kcal × 1.2). On dry food at 375 kcal/100 g that's about 75 g a day — roughly 37 g per meal, twice a day. Cats do best with measured meals rather than a topped-up bowl; free-feeding kibble is a leading cause of feline obesity.
| Energy need (MER) | ≈281 kcal |
|---|---|
| Dry food/day | ≈75 g |
| Per meal | ≈37 g × 2 |
- Measured meals Beat free-feeding
- Neutered ×1.2 factor
Why wet food portions look huge Same cat: ≈ 312 g/day wet
That same 5 kg cat needing 281 kcal eats about 312 g a day of wet food — over four times the dry-food weight — simply because canned and pouch food is 75–85% water (~90 kcal/100 g) versus ~375 for kibble. The calorie need is identical; only the density changed. So never copy a dry-food gram figure onto wet food — match the portion to the energy on the tin.
| Wet density | ≈90 kcal/100 g |
|---|---|
| Dry density | ≈375 kcal/100 g |
| Wet food/day | ≈312 g |
- Same calories ~4× the weight
- Mixing? Split the calories
Puppy portions (10 kg, 4–12 months) ≈ 197 g/day, 3 meals
Growing dogs burn far more energy per kilo. A 10 kg pup aged 4–12 months uses a ×2.0 growth factor: RER 394 kcal × 2.0 = 787 kcal/day, or about 197 g of 400 kcal/100 g puppy dry food — split across three meals (~66 g each). Recheck the amount every couple of weeks as they grow, and use a puppy-formulated food, not adult.
| Growth factor | ×2.0 |
|---|---|
| Energy need | ≈787 kcal |
| Food/day | ≈197 g, 3 meals |
- Under 4 months ×3.0, 3–4 meals
- Reassess Every 2 weeks
Active or working dog (30 kg) ≈ 598 g/day
A hard-working 30 kg dog can need a ×2.5 factor (working dogs range 2.0–5.0). RER 897 kcal × 2.5 = about 2,244 kcal/day — roughly 598 g of 375 kcal/100 g dry food. Working and sporting dogs may need even more on heavy days; feed to maintain a lean, athletic body condition rather than to a fixed number.
| Activity factor | ×2.0–5.0 |
|---|---|
| Energy need | ≈2,244 kcal |
| Food/day | ≈598 g |
- Heavy work days Feed more
- Rest days Feed less
Feeding for weight loss Use the TARGET weight
The key nuance: a weight-loss plan is calculated on the ideal (target) weight, not the current weight. A cat now 5 kg but ideally 4 kg uses RER of 4 kg (198 kcal) × 0.8 = 158 kcal, about 42 g of dry food a day — well below its current maintenance. A dog from 25 kg to a 22 kg target uses ×1.0 on 22 kg ≈ 190 g/day, roughly a third less food. Always vet-supervise weight loss.
| Basis | Target weight |
|---|---|
| Cat 5→4 kg | ≈42 g/day |
| Dog 25→22 kg | ≈190 g/day |
- Slow & steady Vet-supervised
- Weigh food Don't eyeball
Small dog (4 kg) ≈ 84 g/day
A neutered 4 kg small-breed dog needs about 317 kcal a day (RER 198 × 1.6) — roughly 84 g of 375 kcal/100 g dry food, about 42 g per meal. Small breeds burn more energy per kilo than big dogs (the 0.75 exponent captures this), so don't just scale a big-dog portion down by weight — use the equation.
| Energy need | ≈317 kcal |
|---|---|
| Food/day | ≈84 g |
| Per meal | ≈42 g × 2 |
- Per-kilo need Higher than big dogs
- Toy breeds Watch for low blood sugar
Reading the energy off a pet-food label kcal/kg ÷ 10
US pet-food labels carry an AAFCO calorie content statement, which gives metabolizable energy as kcal/kg and usually kcal per cup as well. To use it here, divide kcal/kg by 10: a food listed at 3,750 kcal/kg is 375 kcal/100 g. This single number — not the brand or the price — is what sets the portion, and it varies a lot (dry 300–450, wet 70–130). Weighing in grams is far more accurate than scooping cups, since cup weight changes with kibble size. Type your bag's figure into the energy-density field for an accurate result.
| Label shows | kcal/kg + kcal/cup |
|---|---|
| Convert | ÷ 10 → kcal/100 g |
| Weigh, don't scoop | Cups vary |
- Every food differs Always check
- No kcal on bag? Ask the maker
Worked examples
| Inputs | Food per day | Note |
|---|---|---|
| A 20 kg neutered dog on dry food, two meals | 282 g | RER 662 kcal, MER 1,059 kcal, 282 g a day |
| A 4 kg neutered cat on wet food | 264 g | about 264 g a day |
| Weight loss to a 25 kg target with 10% treats | 188 g | fed to the target weight at factor 1.0 |
FAQFrequently 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. Sources
The sources behind this calculator
- American Association of Feline Practitioners — Feline Life Stage Guidelines — the six feline life stages the cat-age page uses
- Wang et al. 2020, Cell Systems — Quantitative translation of dog-to-human aging by conserved remodeling of the DNA methylome — the 16·ln(age)+31 epigenetic formula on the dog-age page
- US Department of Labor — Tipped employees — the tipped minimum wage rules
Last checked: September 2026. Where a page states a convention (a tipping custom, a pet life stage), the page names the body it follows.