Male Giraffes can grow up to 18 feet tall, females Giraffes can reach 14 feet tall and their babies, called calves, are born around 6 feet tall. Calves can grow up to an inch a day. In the wild, giraffes will sleep only about 20 minutes a day. Giraffes run by moving their front and back legs on one side forward together. Their funny movement makes them pretty fast. The record running speed of a giraffe is 34.7 mph