Testicle Size Difference: What's Normal and When to Worry

Normal Variation

It is normal for one testicle to be slightly larger than the other. A difference of up to 1 cm (about the size of a pea) is common and usually not noticeable. The left testicle often hangs lower and may be slightly larger.

Potential Medical Causes of Significant Asymmetry

• Testicular cancer – most serious; typically presents as a painless hard lump, heaviness, or change in consistency/size.
• Varicocele – dilated pampiniform plexus veins (usually left side), causing a "bag of worms" feel and possible size increase.
• Hydrocele – fluid accumulation around the testicle, painless swelling.
• Epididymo-orchitis – infection/inflammation causing painful enlargement.
• Inguinal hernia – abdominal contents extending into scrotum.
• Testicular torsion – acute, severe pain with sudden swelling (surgical emergency).
• Hormonal disorders – e.g., Klinefelter syndrome (small, firm testes).

When to Consult a Doctor

• New or enlarging lump.
• Persistent ache or heaviness.
• Sudden severe pain (torsion = emergency).
• Change in texture (hardness).
• Any concern—clinical exam and scrotal ultrasound provide rapid reassurance or diagnosis.

Monthly testicular self-exams (after a warm shower) help detect changes early.