What is the standard size of the penis?

Patient's question:

How big does the penis need to be to be considered normal

Doctor's answer:

Just like height and weight vary greatly among individuals, the penis size also shows significant individual differences. Shi Chengli from China once measured the penis size of 1,412 healthy Chinese young men and the erect length of 26 healthy males.
The results showed that in a normal state, the longest penis measured 14.5 cm, the shortest 4 cm, with an average of 8.375 cm. The circumference ranged from a maximum of 12 cm to a minimum of 4.5 cm, with an average of 8.3 cm. During erection, the longest penis reached 16 cm, the shortest 9 cm, with an average of 12 cm. A penis measuring 4 cm or 14 cm in a non-erect state is normal for adult males. An erect penis measuring 9 cm or 16 cm is also normal.