How big was a T. rex?
Tyrannosaurus rex was about 40 to 43 ft12 to 13 m1 long, a grown-up, nose to tail; scientists' estimate. One of the biggest meat-eating dinosaurs, with a huge head and tiny arms.
Tyrannosaurus rex next to you
Next to a child about four feet tall: Tyrannosaurus rex is about 11 of you long, lying head to toe.
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Where the numbers come from
- USDA Forest Service, Dakota Prairie Grasslands: prehistoric animals, checked 30 October 2026.