Why are my testicles different sizes?

Question:

Could you explain why one of my testicles is at 4.1 Cm (Start of Tanner Stage 4) while my other one is about 4.6 cm (Tanner 5)? If so, where would I put myself?

Answer:

While we would like to think of ourselves as perfectly symmetrical, the truth is that we rarely are. Most of the differences between the left and right sides of our bodies are usually minor, but sometimes, a difference is notable.

It is common in men for one testicle to be bigger than the other. Usually, it is the right testicle that is larger due to that testicle developing in the womb before the other. A slight difference is not a concern (less than 20%), and even larger differences (it can reach as high as 50%) are not uncommon. Especially during adolescence, these differences in size can change as you develop. However, a doctor should check out any difference accompanied by pain or discomfort. Often, guys confuse a swelling next to the testicle with being part of the testicle and so think that the testicle is bigger. Diseases such as epididymitis or orchitis can make a testicle swollen. However, diseases usually have other symptoms, such as pain or discomfort.