Diet calculator: how much would an animal eat
How many shrimp would your cat eat and how many zebras a lion needs — scaled by metabolism: small animals need more food per kilogram.
Who eats whom
- Who eats whom: human and hippo
- What if a human ate an African elephant?
- Who eats whom: domestic cat and rat
- What if a lion ate a blue wildebeest?
- Who eats whom: German boxer and hedgehog
- What if a goshawk ate a rock dove?
- Who eats whom: Nile crocodile and plains zebra
- What if a domestic cat ate a great spotted woodpecker?
- Who eats whom: great white and common seal
- What if a dog ate a common frog?
- Who eats whom: grizzly and Atlantic salmon
- What if a Siamese ate a red squirrel?
Pets and food
- How long would it take a hamster to digest a mouse?
- How much of a brown hare would a Borzoi actually eat?
- Will it even come out? A Bengal cat ate a mouse!
- How long would it take a Labrador retriever to eat a brown hare?
- Domestic cat and rat: how much gets eaten, absorbed and turned into 💩
- Could a German boxer eat a hedgehog — and how long would it take?
- Who eats whom: domestic cat and great spotted woodpecker
- What if a dog ate a common frog?
- A Siamese swallowed a red squirrel — how long until it comes out?
How long the meal takes
- A sperm whale swallowed a giant squid — how long until it comes out?
- Could a tiger eat a red deer — and how long would it take?
- How long would it take a Burmese python to digest a roe deer?
- How long would it take a jaguar to eat a capybara?
- A pike swallowed a common frog — how long until it comes out?
- Could a bullfrog eat a mouse — and how long would it take?
- How long would it take a brown bear to digest an elk?
- How long would it take a killer whale to eat a southern elephant seal?
- A Komodo dragon swallowed a Javan rusa — how long until it comes out?
- Could a rat eat a mouse — and how long would it take?
- How long would it take a Eurasian eagle-owl to digest a brown hare?
- How long would it take a goshawk to eat a red squirrel?
How long it lasts
- How long would one hippo keep a human going?
- How much of an African elephant would a human absorb?
- How much of a rat would a domestic cat actually eat?
- How many lions can one blue wildebeest feed?
- How many hedgehogs does a German boxer need to get full?
- How long would one rock dove keep a goshawk going?
- How much of a plains zebra would a Nile crocodile absorb?
- How much of a great spotted woodpecker would a domestic cat actually eat?
- How many great whites can one common seal feed?
- How many common frogs does a dog need to get full?
- How long would one Atlantic salmon keep a grizzly going?
- How much of a red squirrel would a Siamese absorb?
What comes after
- Will it even come out? A human ate a hippo!
- Human and African elephant: how much gets eaten, absorbed and turned into 💩
- How much 💩 if a domestic cat ate a rat?
- Whatever you eat, it all ends up as 💩. How much if a lion eats a blue wildebeest?
- Turning a hedgehog into 💩: how much would a German boxer make?
- Rock dove in, 💩 out: how much and how soon, with a goshawk doing the eating
- Will it even come out? A Nile crocodile ate a plains zebra!
- Domestic cat and great spotted woodpecker: how much gets eaten, absorbed and turned into 💩
- How much 💩 if a great white ate a common seal?
- Whatever you eat, it all ends up as 💩. How much if a dog eats a common frog?
- Turning an Atlantic salmon into 💩: how much would a grizzly make?
- Red squirrel in, 💩 out: how much and how soon, with a Siamese doing the eating
Calculator
How it works
Answers the question: if the target organism "ate" the model animal, how long would it last. This is not a menu — it is a comparison of the target's daily energy expenditure with the energy stored in the model's body.
Not all of the body is assimilated. Bones, fur, feathers and chitin are counted as ballast. The inedible fraction depends on the taxon: one ratio for a bird, another for a fish, another for an insect.
The result is how long one individual lasts and how many individuals are needed per day.
If the model is a carnivore or omnivore, the comparison can be reversed: see how long the target would last for the model.
We know that an animal's exact birth date is often unknown. That's why the birth-date picker lets you set an approximate range of dates or ages. The finest precision of that range is 15 minutes. We also take time zones into account to work out the birth date as accurately as possible.
How others calculate it: popular "who eats how much" estimates
Today many animals, predators especially, eat things they would never meet in nature. A house cat, a land predator, can eat a shrimp, and an Old World frog in a terrarium can eat a Madagascar hissing cockroach. EatCurculator helps you picture such unexpected pairs: how long the meal takes, whether the eater is full and how many prey animals it needs per day. Here is how others usually answer such questions.
The "percent of body weight" rule: how much food per day
Feeding guides often suggest about 2–3% of body weight per day for a raw-fed dog or cat, and vets estimate daily energy with the RER formula plus factors for activity, neutering and age. These are useful feeding guides, but they tell you the average daily need, not what happens if the animal eats one particular mouse, shrimp or cockroach: how much of it is edible and how long it takes to digest.
"How many antelopes does a lion eat a year": prey-based estimates
Popular articles count the diet of big predators in prey items: so many antelopes a year, so many kilograms of meat at a time. These numbers come from field observations and are good for that species in its habitat. They cannot be moved to another pair, such as a cat and a shrimp or a goshawk and a pigeon: other prey has a different size, energy content and inedible share.
Why simple rules are inaccurate
Neither a body-weight percentage nor a single calorie formula accounts for the part of the prey that is not digested: bones, feathers, fur, insect chitin and crustacean shells. In a shrimp or a cockroach that share is noticeable; in a fillet it is almost zero. They also ignore the eater's own life stage and mass: a kitten and an adult cat eat differently, and a python may digest a large meal for weeks. Finally, everyday "who eats whom" lists often mix real hunting relationships with what an animal is merely able to swallow.
How EatCurculator calculates
EatCurculator takes the mass of the eater and the prey with their age and life stage, estimates the eater's daily need, subtracts the inedible fractions of the prey and shows how long digestion takes, how long satiety lasts and how many such animals are needed per day. For pairs that occur in nature this is close to reality; for pairs from the domestic world, such as a cat and a shrimp, it is a careful model of what could happen.
The future of EatCurculator: diet and lifespan
Diet strongly affects lifespan: overweight animals and animals on unsuitable food live shorter lives on average, while a balanced diet helps them stay healthy longer. Next we want to link EatCurculator with AgeCurculator: take the usual diet into account in lifespan forecasts, add more foods that pets really get, and describe digestibility more precisely. We collect data from veterinary and zoological scientific papers and databases, as well as user data. If you want to help, keep a pet diary on Zveriki with diet and weight; more on age is on the AgeCurculator hub.