What is the normal penis size for 13 year old?
There is no "normal". The size you are is normal for you.
The average penis size for a 14 year old is about 4 inches. HOWEVER, the age at which puberty typically begins is anywhere between 10 and 15 years old. So the penis size for a 14 year old can range from prepubertal (About 2 inches) to Adult (6+ inches). At 14 years old it would be normal to have a penis anywhere in that range.