Why Is One Testicle Larger Than the Other?

A healthy male has two testicles, one located in the left side of the scrotum and the other in the right. Generally, both testicles feel roughly the same size upon palpation, and their size difference is barely noticeable to the naked eye. In most healthy males, the right testicle is slightly larger than the left and sits at a slightly higher position. As long as both testicles fall within the normal size range, this asymmetry is considered physiologically normal. So, what causes one testicle to be noticeably larger than the other? Below, we address this question.

Why Is One Testicle Larger Than the Other?

1. Physiological Variation

Typically, the right testicle is slightly larger than the left. Even among males of the same age group, natural variation in testicular size is common. Therefore, if the size difference between the two testicles is minor, no cause for concern exists.

2. Testicular Trauma

Trauma to the testicles—such as from accidents or injuries—can also lead to asymmetry in size. Following injury, intratesticular hemorrhage or hematoma may develop; in severe cases, compromised blood supply can result in progressive testicular atrophy, thereby producing noticeable size asymmetry.

3. Orchitis

Severe orchitis (inflammation of the testicle) may cause testicular atrophy, resulting in asymmetry. If accompanied by localized pain, swelling, or systemic symptoms such as fever, orchitis is a likely diagnosis.

4. Testicular Disorders

Significant asymmetry in testicular size warrants evaluation for underlying testicular pathology. Common conditions include orchitis, testicular cysts, and cryptorchidism (undescended testicle). Patients often report associated symptoms such as testicular pain, a sensation of heat or burning, and swelling. In rare but serious cases, testicular cancer may be responsible—thus prompt clinical evaluation and diagnostic testing are essential.

The above outlines potential causes of testicular size asymmetry. We hope this information is helpful to you.