Changes in Testicle Size: What's Normal and Your Action Plan

Noticing a change in testicle size can be unsettling. Many men wonder: Is one testicle smaller in old age? Or, "Has something serious developed?"

The truth is that some variation in testicle size is completely normal — especially with aging. However, certain changes should never be ignored. This guide explains what's normal, what's not, and exactly what to do next.

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Is It Normal for One Testicle to Be Bigger Than the Other?

Yes.

It is very common for one testicle to be slightly larger or hang lower than the other. In fact:

• The left testicle is often slightly lower than the right.
• Small size differences (a few millimeters) are typical.
• Mild asymmetry is usually present from puberty onward.

As long as:

• The size difference has been stable
• There is no pain
• There are no lumps
• There are no sudden changes

…it is usually not a cause for concern.

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Is One Testicle Smaller in Old Age?

A common question is: Is one testicle smaller in old age?

Yes — testicles naturally decrease in size somewhat as men age.

Why does this happen?

As men get older:

• Testosterone production gradually declines.
• The sperm-producing tissue becomes less active.
• Testicular tissue may shrink slightly (a process called testicular atrophy).

This shrinkage is usually:

• Gradual
• Mild
• Occurring in both testicles

If one testicle becomes significantly smaller than the other, especially over a short period of time, that is not typical aging and should be evaluated.

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What Is Considered a Normal Testicle Size?

In adult men:

• The average testicle measures about 4–5 cm long
• Volume is typically 15–25 milliliters
• Minor differences between sides are common

Size alone isn't the only factor. Doctors also assess:

• Firmness
• Texture
• Presence of lumps
• Tenderness
• Changes over time

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Common Causes of Testicle Size Changes

Let's break down the most common reasons testicle size may change.

1. Aging

As mentioned, gradual shrinking can happen with age due to lower testosterone production. This is typically:

• Slow
• Painless
• Symmetrical (both sides affected)

2. Varicocele

A varicocele is an enlarged vein in the scrotum (similar to a varicose vein in the leg). It is common and often occurs on the left side.

It may cause:

• One testicle to appear smaller
• A dull ache
• A heavy feeling in the scrotum

Varicoceles can sometimes affect fertility but are often harmless.

3. Previous Injury

A past injury to one testicle may result in:

• Gradual shrinkage
• Scar tissue formation
• Reduced function

Even an injury from years ago can cause long-term size changes.

4. Infection (Orchitis or Epididymitis)

Infections can cause:

• Swelling at first
• Pain
• Fever
• Later shrinkage if damage occurs

Prompt treatment usually prevents long-term problems.

5. Hormonal Issues

Low testosterone or certain hormonal disorders can cause:

• Smaller testicles
• Reduced libido
• Fatigue
• Loss of muscle mass

6. Testicular Torsion (Emergency)

This occurs when the spermatic cord twists and cuts off blood supply.

Symptoms include:

• Sudden severe pain
• Swelling
• Nausea
• One testicle sitting higher than usual

If untreated, the testicle can shrink due to tissue damage. This is a medical emergency.

7. Testicular Tumor

Testicular cancer does not always cause pain. Early signs can include:

• A painless lump
• A feeling of heaviness
• A firm area
• Subtle enlargement
• Rarely, shrinkage in surrounding tissue

Testicular cancer is highly treatable when caught early. If you're experiencing any of these symptoms, taking a free symptom checker test can help you understand your symptoms better and guide you on whether medical attention is needed right away.

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When Is a Change NOT Normal?

You should speak to a doctor if you notice:

• Sudden size change
• Rapid shrinkage of one testicle
• A new lump
• Persistent pain
• Swelling
• Hardening of the testicle
• A feeling of heaviness that doesn't go away
• A change in firmness
• Unexplained fertility issues

Even if it turns out to be harmless, getting checked provides peace of mind.

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What About Shrinking After Illness or Steroid Use?

Certain medical treatments or medications can cause testicle shrinkage, including:

• Anabolic steroids
• Testosterone therapy (without proper medical supervision)
• Chemotherapy
• Radiation

Steroid use suppresses the body's natural testosterone production, which can lead to noticeable testicle shrinkage. In some cases, this may be reversible after stopping use under medical guidance.

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How to Check Your Testicles at Home

Monthly self-checks help you recognize changes early.

How to perform a self-exam:

• Do it after a warm shower (skin is relaxed).
• Hold one testicle at a time.
• Gently roll it between your fingers.
• Feel for lumps, hardness, or changes in texture.
• Note any differences from the previous month.

Normal findings include:

• A soft, tube-like structure at the back (epididymis)
• Slight size differences between testicles

You are looking for new changes, not natural asymmetry.

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What Will a Doctor Do?

If you visit a doctor about testicle size changes, they may:

• Perform a physical exam
• Order an ultrasound (safe and painless)
• Check hormone levels
• Run blood tests
• Evaluate for infection
• Assess fertility if relevant

An ultrasound is especially useful and can quickly rule out serious conditions.

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Does Smaller Mean Less Masculine?

Absolutely not.

Testicle size varies widely among men and does not define masculinity, strength, or worth. While size can influence sperm production, it is only one part of reproductive health.

If fertility is a concern, a semen analysis can provide accurate answers.

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Your Action Plan

If you've noticed a change in testicle size, here's a calm and practical approach:

✅ Step 1: Assess the Change

• Has it always been this way?
• Was the change gradual or sudden?
• Is there pain?

✅ Step 2: Monitor Briefly (If No Red Flags)

If there is:

• No pain
• No lump
• No rapid change

You can monitor for a few weeks.

✅ Step 3: Use a Trusted Symptom Checker

If you're unsure about your symptoms or need help deciding your next steps, Ubie's AI-powered symptom checker can provide personalized guidance in just a few minutes.

✅ Step 4: Speak to a Doctor

Seek medical care promptly if:

• The change is sudden
• There is pain
• A lump is present
• You feel something "just isn't right"

Early evaluation makes treatment simpler and more effective.

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The Bottom Line

• Mild differences in testicle size are normal.
• Yes, one testicle can be smaller in old age due to natural aging.
• Gradual, symmetrical shrinkage is common with lower testosterone.
• Sudden or one-sided shrinkage is not typical aging.
• Pain, lumps, or rapid changes should always be checked.

Most testicle size changes are not cancer, and most causes are treatable. But ignoring significant changes is never the right move.

If something feels different, unusual, or concerning, speak to a doctor. Testicular conditions — including cancer — are highly treatable when detected early. Getting evaluated is not overreacting; it's responsible.

Your health is worth the conversation.