Testosterone levels by age: What is the normal range?

Testosterone is a key hormone for both men and women, although its roles and
normal levels differ significantly depending on sex and age. In men especially,
testosterone levels vary greatly with age and affect overall health, sexual function, and
quality of life. But which levels are considered normal and which are not?

What is testosterone?

Testosterone is an androgenic hormone—part of the group of steroid hormones responsible for the development of sex characteristics. It is primarily produced in the testes in men and the ovaries in women, while small amounts also come from the adrenal glands in both sexes.

Although often associated with men, testosterone is also important for women. The main difference lies in quantity: women typically have 10 to 15 times less testosterone than men.

The role of testosterone in the body

Testosterone contributes to many physical and mental functions.

In men:

• Promotes development of genital organs and sperm production
• Contributes to muscle strength and bone density
• Affects libido, mood, and energy
• Regulates characteristics like voice depth and body hair

In women:

• Helps regulate mood
• Supports sexual desire
• Aids in red blood cell production
• Influences bone and muscle health

Normal testosterone levels by age

Testosterone is usually measured through a blood test, with results expressed in nanograms per deciliter of blood (ng/dL). Normal ranges differ based on sex and age.

Therefore, normal testosterone levels by age are as follows:

0–5 months: 75 – 400 ng/dL

Testosterone is relatively high due to the so-called “mini puberty” of infancy.

6 months – 9 years: <7 – 20 ng/dL

Testosterone levels are very low because the endocrine system is inactive in childhood.

10 – 11 years: <7 – 130 ng/dL

Pre-puberty begins so levels may gradually rise.

12 – 13 years: <7 – 800 ng/dL

Sharp increase signals the onset of puberty.

14 years: <7 – 1.200 ng/dL

Puberty is underway so levels approach adult norms.

15 – 16 years: 100 – 1.200 ng/dL

Testosterone production stabilizes at near-adult levels.

17 – 18 years: 500 – 1.200 ng/dL

Full maturation of the endocrine system; adult levels reached.

19+ years: 240 – 950 ng/dL

Adult male levels. These remain relatively stable until around age 30–40, after which a gradual decline begins.

Testosterone in adulthood and aging

Testosterone production spikes during puberty, peaks around age 20, and then declines by about 1–2% annually after age 30.

According to the American Urological Association:

• 2 in 10 men over 60 have low testosterone
• 3 in 10 men over 70–80 show significant hormonal decline.

This phenomenon is sometimes referred to as “male menopause” or andropause, although the decline is usually gradual—not abrupt like female menopause.

Causes of low testosterone levels

Besides age, there are many factors that can lead to low testosterone:

• Testicular injury or disease
• Cancer and its treatments (chemotherapy/radiation)
• Infections (such as HIV/AIDS)
• Hormonal disorders (e.g., hypogonadism)
• Obesity and type 2 diabetes
• Chronic liver or kidney disease
• Excessive alcohol consumption
• Lack of sleep and intense stress
• Certain medications (e.g., corticosteroids)

Daily fluctuation of testosterone levels

Testosterone levels are not constant throughout the day. They are highest in the early morning (between 4:00–8:00 AM) and gradually decrease by evening. For this reason, blood tests should be done in the morning for the most reliable results.

Can diet affect testosterone levels by age?

Although testosterone production is tightly regulated by the brain (hypothalamus-pituitary axis), diet can indirectly help maintain normal levels.

The Mediterranean diet, rich in healthy fats (olive oil, nuts), proteins (fish, legumes), and complex carbs (whole grains), seems to better support hormonal balance compared to low-fat diets. A lack of dietary fat can impair hormone production.

Can testosterone levels be increased naturally?

No, at least not safely and permanently without medical intervention. The body regulates testosterone through a feedback mechanism, meaning even if someone temporarily increases levels via diet or exercise, they will soon normalize again.

What can help is preventing unnecessary decreases through:

• Adequate sleep and rest
• A healthy diet with good fats (e.g., Mediterranean diet)
• Regular physical activity, especially weight training
• Reduced stress and alcohol intake.

What about testosterone-boosting supplements?

Most supplements claiming to boost testosterone lack proven effectiveness. Except in medically diagnosed cases of hypogonadism, testosterone should only be taken under medical supervision and prescription.

Medical administration of testosterone to restore normal levels of testosterone by age

If it is medically confirmed that testosterone levels are indeed low, then the option of testosterone increase through exogenous hormone administration can be considered. In such cases, testosterone replacement therapy (TRT therapy) may be evaluated, with the goal of restoring testosterone to normal levels and improving quality of life. MenTest is a specialized medical center in Greece dedicated to addressing low testosterone and its effects on men’s health. The medical team, led by specialist andrologist-urologist Dr. Christos Fliatouras, applies modern therapeutic methods tailored to each patient’s needs, aiming to improve quality of life and overall well-being.

In conclusion, testosterone is a crucial hormone for men’s overall health. Testosterone levels vary with age and are influenced by many factors. In men, a natural decline after the age of 30 is expected; however, when the drop is significant and accompanied by symptoms, medical evaluation is warranted.

If you are seeking information about the recommended testosterone levels by age, make sure to consult an endocrinologist or urologist. Do not trust unapproved supplements or questionable treatments that have not been prescribed by a specialist.