T. rex were roughly 12–13 feet (about 3.6–4 meters) tall at the hips, and would have reached a bit over 20 feet (about 6.5 meters) tall if they could stand fully upright.

They are also estimated to have been around 40 feet (about 12 meters) long from nose to tail, weighing several tons, which made them among the largest land predators to ever live.