There are 5 Stages

1. Penis and testicles of a child. Testicles between 1 and 3 milliliters in volume.
   
2. First signs for penis, testicle growth, and pubic hair beginning to grow. Penis doesn’t growth is small. Testicles become larger. Testicles between 4 and 6 milliliters in volume.
   
3. Penis continues to grow getting wider and longer. Testicles continue to grow larger. Testicles between 7 and 16 milliliters in volume.
   
4. Penis continues to grow getting wider and longer. Testicles continue to grow larger. Penis glan or head is more developed. Testicles between 12 and 24 milliliters in volume. Testicles are about 1 1/2 inches long.
   
5. Penis growth enters finial stage. Average erect penis length 6 1/4 inches. Ninety percent are between 5 and 7 inches. Pubic hair is thick. Penis glan or head is fully developed. Testicles between 16 and 27 milliliters in volume. Testicles are about 1 3/4 inches long.
   

Credit: J. Geoff Malta, MA, EdM, NCC Adolescent Therapist