Calves grow quickly. In the first year of birth, calves average 92 to 112 cm (36-44 in.). One-year-old calves are about 99 to 117 cm. (39-46 in.). Compare this to the average adult length of 120 to 170 cm (47-67 in.) and you'll see that a large one-year-old can be virtually the same size as a small adult.