Dog food calculator
A 20 kg four-year-old dog eating a 350 kcal-per-cup kibble needs about 3.03 cups, or 314.7 g, a day, based on resting energy and a life-stage factor. Enter weight, age and the bag's calories per cup. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Weight (kg)
- 20
- Age (years)
- 4
- Kcal per cup
- 350
- Age category
- adult
- Rer kcal
- 662.02
- Mer factor
- 1.6
- Daily kcal
- 1,059.2
A dog food calculator turns three household facts — how heavy the dog is, which age category that weight sits in, and how energy-dense the bag is — into a daily ration you can scoop. Veterinary feeding charts start from resting energy, the exponential rule seventy times body weight in kilograms to the three-quarters power, then scale that rest figure by a life-stage factor so a growing puppy is not fed like a quiet senior. Divide the resulting daily kilocalories by the metabolizable energy printed on the food, in kilocalories per US cup, and you have cups per day; multiply those cups by one hundred and four grams, the conventional mass of a level dry-kibble cup, and you have grams.
How weight, age category and caloric density become a daily ration
Veterinary feeding plans for domestic dogs start from resting energy requirement, not from a human calorie table and not from the scoop printed on a marketing panel. The exponential resting energy formula used in small-animal nutrition is RER equals seventy times body weight in kilograms raised to the power of three-quarters. That three-quarters exponent is the metabolic scaling of Kleiber's law applied to a mammal whose surface-to-mass ratio is not linear in kilograms, so a twenty kilogram adult does not need twice the energy of a ten kilogram dog.
Once RER is known, an age-category factor converts rest into a maintenance energy requirement, MER. Puppies from four months to one year use 2.0. Adults from one year up to seven years use 1.6, the usual neutered-adult coefficient.
A twenty kilogram four-year-old on a three-hundred-and-fifty kilocalorie cup therefore lands near three cups, a few hundred grams, which is the order of magnitude a clinic feeding chart would quote before you still confirm body-condition score with a veterinarian. The linear shortcut thirty times kilograms plus seventy is not used here: it drifts on puppies and on giant or toy bodies where the three-quarters power law is the published veterinary default.
Where a dog food calculator earns its keep
Homes that have just adopted a medium adult use a dog food calculator so the first week of feeding is not a guess copied from the neighbour's Labrador. Rescue intake desks and clinic front desks batch weight, age, and the bag's kcal per cup from the card and need a deterministic oracle that rejects a zero-kilogram paste instead of silently publishing a zero-cup ration. Puppy foster programmes need the growth band (age under one year) to raise the multiple without someone memorising a wall chart for four months versus six.
Failed validation does not consume balance. Keep the three inputs honest, pin cups and grams in tests, and you get a reproducible daily portion for homework, LMS plugins, shelter spreadsheets, and feeding apps. Related searches for a human TDEE table, a dog-age-in-human-years conversion, a cephalexin milligram dose, or a cat calorie target are different intents: stay on this page when the question is only the dog's daily food portion implied by weight, age category, and caloric density.
This estimate is educational and does not replace a veterinarian, especially for obese, underweight, pregnant, lactating, or clinically ill dogs whose coefficients sit outside the four age bands.
What you can do with it
Adult dry-food daily scoop
Enter the dog's weight in kilograms, adult age, and the bag's kcal per cup to get a daily cup and gram target you can split across morning and evening meals.
Puppy growth rations
Foster and clinic intake cards for dogs under one year use the puppy age factor so the daily portion rises with growth instead of copying an adult indoor chart.
FAQ
What if weight, age, or caloric density is zero or negative?
Every input must be a finite positive number; missing fields, empty strings, and non-numeric values are rejected the same way and are not billed.
How are cups converted into grams?
A level US measuring cup of dry kibble is taken as 104 grams. grams is cups times 104, so a three-cup ration is 312 grams. Wet food whose cup mass differs should be portioned from the gram figure and the can label.
How many calories does my dog need per day?
Start from resting energy, 70 times the weight in kilograms to the three-quarters power, then multiply by the life-stage factor. A 20 kg four-year-old adult comes to 1059.2 kcal a day.
Why do puppies get more food per kilogram than adult dogs?
Growth, keeping warm and play raise their needs. Puppies under four months use a factor of 3.0 and those from four months to one year use 2.0, against 1.6 for adults and 1.2 for seniors.
Why not use the 30 times weight plus 70 shortcut?
That linear shortcut drifts for puppies and for toy or giant dogs. The three-quarters power rule is the published veterinary default, so a 20 kg adult does not simply need twice the energy of a 10 kg dog.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/bio/dog-food \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"weight_kg":20,"age_years":4,"kcal_per_cup":350}'const res = await fetch("https://api.kit.forhosting.com/bio/dog-food", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"weight_kg": 20,
"age_years": 4,
"kcal_per_cup": 350
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/bio/dog-food",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"weight_kg": 20,
"age_years": 4,
"kcal_per_cup": 350
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/bio/dog-food", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"weight_kg":20,"age_years":4,"kcal_per_cup":350}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"weight_kg":20,"age_years":4,"kcal_per_cup":350}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/bio/dog-food", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"weight_kg": 20,
"age_years": 4,
"kcal_per_cup": 350
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "bio.dog_food",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Limits
max_weight_kg | 120 |
max_age_years | 25 |
max_kcal_per_cup | 800 |
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Enter weight_kg, age_years, and kcal_per_cup as finite positive numbers.
How weight, age category and caloric density become a daily ration
Puppies younger than four months, meaning age_years below four twelfths, use a mer_factor of 3.0 because growth, thermoregulation, and play dwarf adult maintenance. Seniors from seven years use 1.2 because many older dogs lower their daily expenditure. daily_kcal is that product. The food's caloric density, kcal_per_cup, is the metabolizable energy printed on the bag; cups equals daily_kcal divided by kcal_per_cup. grams equals those cups times one hundred and four, a conventional mass for a level US cup of dry kibble.
Input contract, response shape, and error behaviour
A six-month puppy of eight kilograms on a denser bag is still in the puppy band and therefore needs a larger multiple of its smaller rest figure. POST a JSON body with three required fields, and every one of them must be a finite positive number. weight_kg is the dog's body mass in kilograms (aliases weight, kg, mass_kg) and must sit in the open-closed interval from just above zero through one hundred and twenty; a two-hundred-gram newborn puppy is legal, a zero or negative paste is not. age_years is age in years (aliases age, years, age_category), a finite positive number no greater than twenty-five; use a fraction for puppies so that 0.25 is three months and 0.5 is six months. That number is not a free-text label: it selects the age category that the response names as puppy, adult, or senior. kcal_per_cup is the food's caloric density in metabolizable kilocalories per US measuring cup (aliases kcal, calories_per_cup, density), a finite positive number no greater than eight hundred; typical dry kibble sits near three hundred to four hundred and fifty. Each field may arrive as a JSON number or as a numeric string. Missing fields, empty strings, non-finite values, zero, negatives, and values above the declared maxima fail with invalid_input naming the field. Those failures are not billed. On success the body echoes the cleaned weight_kg, age_years, and kcal_per_cup, publishes age_category, reports rer_kcal as resting energy rounded to two decimals, reports mer_factor as the life-stage multiplier, reports daily_kcal as the maintenance target, and returns cups rounded to two decimals and grams rounded to one decimal. formula restates RER, the age-scaled MER, the cup division, and the one-hundred-and-four-gram conversion. Example: weight_kg 20, age_years 4, kcal_per_cup 350 is an adult on ordinary dry food. Pair cups and grams with the feeding schedule you already use; this endpoint does not score body condition or split meals.
Where a dog food calculator earns its keep
Exam-prep generators and student nutrition katas pin a known adult, a known puppy, and the invalid_input path for a non-positive weight so a buggy grader cannot accept a negative scoop.
Integration use cases
Switching bags without guesswork
When caloric density changes from one formula to the next, keep weight and age fixed and recompute cups and grams from the new kcal_per_cup so the energy intake stays the same.
Technical questions
How do I calculate how much dog food to feed per day?
Send finite positive numbers for weight_kg, age_years, and kcal_per_cup. The API returns daily_kcal from RER times the age-category factor, then cups = daily_kcal / kcal_per_cup and grams = cups × 104.
Which age categories does the calculator use?
age_years under four months is a young puppy (factor 3.0), under one year is a puppy (2.0), from one year up to seven years is adult (1.6), and seven years and older is senior (1.2).
What does the dog food calculator cost?
The browser tool is free. API requests use prepaid KIT balance at $0.002 per successful call; invalid input is not billed.