How Many Calories Would a T-Rex Get From Eating You?

Find out how many T-Rex meals you'd make — and how long you'd feed one.

Frequently asked questions

How many calories did a T-Rex need per day?

Scientists estimate adult Tyrannosaurus rex required around 40,000 calories per day to maintain its 8-tonne body — about 20× a modern adult human. Like most apex predators, it likely ate in big sporadic meals rather than continuously.

How long would a human feed a T-Rex?

A 75 kg human contains roughly 135,000 calories of food energy. That's about 3.4 days of T-Rex maintenance feeding. Not enough to sustain it for long — T-Rex required prey on the order of multiple adult humans per week.

What did a T-Rex actually eat?

Mostly hadrosaurs (duck-billed dinosaurs) and ceratopsians (Triceratops and relatives). A single Triceratops could provide an adult T-Rex with two to three weeks of food. T-Rex was both predator and scavenger — bite marks on fossils show both fresh kills and carcasses scavenged from other predators.

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How many calories would a T-Rex get from eating you?

An adult human contains roughly 1,800 calories of food energy per kilogram, comparable to a similar-mass mammal. For a 75 kg adult, that\'s about 135,000 calories of food.

A T-Rex needed about 40,000 kcal/day

Modern palaeontology estimates adult Tyrannosaurus rex required around 40,000 kcal/day at maintenance — based on metabolic scaling from modern reptiles and birds, T-Rex\'s body mass of 6,000–9,000 kg, and presumed activity levels. That puts a single human at roughly 3.4 days of T-Rex food supply — not enough to satisfy the apex predator for long. T-Rex hunted in single-prey events, not continuously.

Prey itemEstimated food energyDays of T-Rex food
Human (75 kg)135,000 kcal3.4 days
Domestic cow (700 kg)1.3M kcal32 days
Adult Triceratops (~9,000 kg)16M kcal400 days
Edmontosaurus (3,000 kg)5.4M kcal135 days

This is part of why T-Rex hunted such enormous prey: to make the energy-per-hunt worthwhile. A predator burning 40,000 kcal/day can\'t make a living catching rabbits.

Could a T-Rex actually catch a human?

Probably yes, despite the famous "T-Rex can\'t see you if you don\'t move" myth from Jurassic Park. Recent palaeontology has revised the T-Rex\'s sensory capabilities significantly: it had binocular vision better than most modern predators, an extraordinarily acute sense of smell (its olfactory bulbs were larger relative to brain size than any other dinosaur), and could likely move at 12–25 km/h — faster than most humans can sustain. Standing still wouldn\'t save you.

T-Rex trivia

  • An adult T-Rex weighed 6,000–9,000 kg and stood 4 metres tall at the hip. The largest known specimen, "Scotty", weighed an estimated 8,800 kg.
  • T-Rex bite force was 35,000–57,000 Newtons — strongest of any land animal ever. Capable of biting through bone like crackers.
  • T-Rex lived 66–68 million years ago in what is now western North America. It was one of the last dinosaurs to evolve before the K-Pg extinction event.
  • The largest known T-Rex skeleton, "Sue", was 12.3 metres long and is on display at the Field Museum in Chicago. She sold at auction in 1997 for $8.36 million.

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