Pet Food Portion Calculator
Estimate how much to feed a dog or cat each day (grams and cups) from body weight, life stage/activity level, and the food's calorie density, using the standard veterinary RER/DER energy formula (RER = 70 x kg^0.75).
Input
Your pet's current body weight
Sets the default calorie density below — check your food label for the exact number
Look for "Metabolizable Energy" on the food label
Output
| Metric | Value |
|---|---|
| No data yet | |
Guides
The Pet Food Portion Calculator estimates how much to feed your dog or cat each day — in grams and cups, plus per meal — based on body weight, life stage/activity level, and the calorie density of the specific food you're feeding. It uses the same resting-energy formula veterinarians rely on, rather than the generic "feeding guideline" chart printed on a bag of food (which assumes an average, moderately active pet and can be off by a wide margin for your individual animal).
How it works
The calculation happens in two steps, following the standard WSAVA/AAHA veterinary energy equations:
Resting Energy Requirement (RER) — the calories your pet would burn at complete rest — is estimated from body weight using the widely used allometric formula:
RER = 70 x (body weight in kg) ^ 0.75Daily Energy Requirement (DER) scales RER by a multiplier for life stage and activity level, since a growing puppy, a working dog, and a neutered couch companion have very different calorie needs relative to their resting metabolism:
DER = RER x life-stage multiplierMultipliers range from 0.8x (weight loss) up to 4.0x (working/high-performance dogs) for dogs, and 0.8x to 2.5x for cats — pick the option that best matches your pet.
The DER is then converted into a food amount using the calorie density you enter (kcal per 100 g, found on the food's label under "Metabolizable Energy" or similar): grams per day = (DER / kcal per 100 g) x 100. Cups are estimated from grams using standard density assumptions — about 120 g per cup for dry kibble (lighter, more air) and about 240 g per cup for wet/canned or raw/home-cooked food (denser, closer to water). These are reasonable averages, not a substitute for weighing food on a kitchen scale, since kibble density varies by brand and shape.
How to use it
- Choose Dog or Cat, and enter your pet's weight (kg or lbs).
- Pick the Life Stage & Activity level that best matches your pet — puppy/kitten, adult (neutered or intact), active/working, senior, or weight-loss.
- Select a Food Type (dry, wet, raw, or custom) — this fills in a typical calorie density, which you should adjust to match the actual number on your food's label.
- Choose how many meals per day you split food into.
- Results update automatically, showing RER, DER, and the recommended portion per day and per meal in both grams and cups.
Working out a feeding plan for a pet that doesn't have a name yet? petname.io can help with that part too.
FAQ
Is this exact for my pet?
No — treat it as a well-grounded starting point, not a prescription. Individual metabolism, breed, climate, health conditions, spay/neuter status, and body condition all shift real-world needs by as much as 20% in either direction. This is a general guideline, not veterinary advice — check with your veterinarian before making significant diet changes, especially for puppies/kittens, pregnant or nursing pets, or pets with medical conditions.
Why do grams and cups sometimes seem inconsistent between foods?
Because cup measurements depend on how dense the food is. A cup of dry kibble weighs much less than a cup of wet or raw food, so always prefer the gram amount when precision matters — a kitchen scale is far more accurate than a scoop.
Is my data sent anywhere?
No. Every value is calculated entirely in your browser — nothing is uploaded or stored.
Use it from code
From 3 credits per callREST API
curl -X POST https://api.iotools.cloud/v1/tool/pet-food-portion-calculator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"petSpecies": "dog",
"weightUnit": "kg",
"weight": "20",
"dogLifeStage": "1.6",
"catLifeStage": "1.2",
"foodType": "dry",
"foodKcal": "350",
"mealsPerDay": "2"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `pet-food-portion-calculator` tool (Pet Food Portion Calculator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.