Men's Health

What Is Free Testosterone?

Fact Checked

Free testosterone is typically the little percentage of the total testosterone concentration in our bodies that isn’t bound to any protein(s).

Last Updated: 12/13/2022

Written by

Warren Dutton

Medically Reviewed by

Dr. Paul Thompson, M.D.

Free testosterone is typically the little percentage of the total testosterone concentration in our bodies that isn’t bound to any protein(s). There are two types of testosterone: 98% bound testosterone and free testosterone, which makes about 2% of the total testosterone in a body. 

Bound testosterone is aligned with the sex-hormone-binding globulin (SHBG), or albumin, while the free variant is available in the veins and unattached from body organs. 

Testosterone is generally the hormone that is primarily responsible for male character development. It is a hormone present in both men and women, with females having a lesser amount in their ovaries. Testosterone plays a huge role in male development, especially at puberty when bodily and psychological changes occur. Thus, testosterone levels affect the build of a man, his voice, mood, and even the development of the penis and testes.

What Is the Importance of Free Testosterone?

Free testosterone works hand in hand with bound testosterone in reproduction and bodily functions. Their levels should be tested to be sure of the amounts present and whether they fit the quota. They help connect with the body's testosterone receptors. A fractional decrease of this hormone may lead to reproductive health issues and failure of primary bodily functions like muscle development.

Bioavailable testosterone is a form of a hormone that is unattached from the organs but still available to use. They act as reserves for where the body needs more testosterone or is facing a reduction. They are more of a backup plan for the body which can fully execute normal functions in case of a decline in testosterone levels.

Additionally, having healthy free testosterone levels can help you achieve optimal testosterone levels. Optimal testosterone has a whole host of benefits, including:

  • Increased libido

  • Increased energy levels

  • Increased lean muscle

  • Decreased fat levels

  • Improved bone density

  • Improved memory

  • Increased concentration

  • Lower cholesterol level

  • Improved insulin sensitivity

  • Endothelial regeneration

  • Plaque removal

  • Improved mood/feeling of well being

  • Improved sleep

  • Decreased risk of prostate cancer

  • Decreased risk of brain inflammation

  • Improved erectile function

Men of all ages can enjoy the benefits of optimal testosterone, so you owe it to yourself to improve your testosterone levels!

Effects of Low Free Testosterone

Low testosterone levels (hypogonadism) is concerning for men given that it's an integral component of their physical and reproductive health. Levels of testosterone, both free and bound, should be taken to account as there are three kinds of testosterone available in a person, including bioavailable testosterone. Since testosterone measurement combines all of these different types into a single figure, a free testosterone reduction may register as a bound testosterone reduction. It is therefore crucial that your urologist does a specific test for both.

Additionally, as free testosterone is linked to total testosterone levels, a reduction in the total levels could translate to a low free testosterone level. Therefore, the ripple effect that occurs when testosterone is low trickles down to deficiency of low free testosterone. The effects of a low amount of free testosterone include:

  • Erectile dysfunction- Problems with penile erection in men occur primarily when there is a problem with the testosterone levels, i.e., below the required level. Increased and prolonged reductions can cause impotence or even infertility.

  • Hormonal imbalance can result when testosterone levels in a man are low. Naturally, the balance of the two human reproductive hormones is self-regulatory, with men having high testosterone and vice versa. Hormonal imbalances lead to abnormal behavior and physical changes in men like moodiness and developing 'man boobs.'

  • Low libido in men.

  • Obesity- Testosterone and estrogen (female reproductive hormone) are related in that when one level is down, the other is high. So, high levels of estrogen in men cause fat to build up as more testosterone converts into estrogen. The buildup is commonly around the abdominal area and can easily cause you to gain weight.

  • Weak bone structure- the bone mass in males is highly dependent on the testosterone levels he has. Therefore a fall in these levels will result in a decrease in bone masse.

  • Fatigue- testosterone is responsible for increased brain activity in men; a reduction causes a feeling of tiredness and lack of vigor.

  • Loss of body hair and facial hair and muscle reduction

Careful mitigation should allow for testing and medication when the above symptoms are experienced. Visit a medical doctor or a urologist to understand the underlying issue fully. Also, cases of low testosterone in older men are typical as testosterone levels degenerate with age. It is therefore advised to treat a low testosterone level in the elderly.

Men between ages 19-49 years generally have levels of 249-836 ng/dL, and those between ages 50+ years have a testosterone measure of 193-740 ng/dL.

Why Should You Test for Free Testosterone Levels?

Obesity, reproductive health, and muscle mass loss are some of the effects of lacking enough testosterone. But sometimes it may be the free testosterone reduction causing these illnesses, not the bound testosterone. Taking a test to check both the bound and the free testosterone will help ascertain what kind of treatment you need.

This test may need to be repeated at different times to get actual test results (pg/L), as fluctuations occur depending on the activity involved during the day. Before the testing, ensure that you don't consume alcoholic drinks, as this may affect your androgen levels and give inaccurate results.

When taking the testosterone level test, you should consider taking other reproductive health tests. The common ones are:

  • Hormonal testing- check for luteinizing hormone (LH), thyroid-stimulating hormone (TSH), Follicle-stimulating hormone(FSH), and prolactin.

  • Sperm(semen) analysis- checks for infertility and sperm count

  • Pituitary gland scan- conducting an MRI on this glad puts into light growths that may be present

Increasing Your Free Testosterone Levels

Increasing normal total testosterone levels also increases your level of free testosterone. Therefore, any practice and exercise that boosts your total testosterone levels is worth pursuing. These include:

1. Physical exercise

Having a good body is not the only upsell for exercising-you add testosterone to your body as well. To achieve this, involve yourself in high-intensity exercise and heavy lifting. The body triggers testosterone production in a bid to grant more muscular gain.

2. Proper dieting

Having balanced meals is the best way to gain equilibrium in the body's functions, allowing the body to convert more protein and vitamins into testosterone. A balanced meal will have appropriate portions of all needed nutrients. Eating healthy food helps fight obesity which reduces the chances of continued estrogen conversion.

3. Quality sleep

The body makes testosterone mainly when we're resting. Less sleep causes the body to postpone testosterone production, which is harmful if the current levels continue to be in use without additions. Doctors recommend 7-8 hours of sleep daily to benefit fully from sleep. 

4. Taking natural supplements

Studies have shown that natural supplements containing minerals and vitamins like vitamin D, magnesium, and zinc lead to increased hormonal production in both men and women.

5. Taking medical prescriptions

After diagnosis, your healthcare provider may advise you to take certain medications to boost your androgen levels. In severe cases of low testosterone, hormones, otherwise known as serum testosterone, are introduced into the body, as the patient can no longer substantively produce testosterone.

It should be noted that increasing testosterone levels also increases blood pressure, which is unfavorable to persons suffering from preexisting conditions such as diabetes.


Free testosterone lurking in the body aids normal body functioning, like muscle mass building and bone structure development. Low levels of this hormone can be associated with obesity, low sex drive, infertility, and fatigue. To counter the problem, one needs to be diagnosed and tested to check the amount of free testosterone present. This way, an appropriate measure is taken to counter the deficiency, thereby rendering you healthy again.

Frequently Asked Questions:

What is a good free testosterone level?

A good level of free testosterone is between 2-5% of the total testosterone. This can be determined by taking a testosterone test which will measure both the levels of bound and free testosterone and check for deficiency.

Can free testosterone be increased?

If you have a low level of free testosterone, you can increase it in several different ways. Participating in rigorous excesses, dieting, avoiding stress, and proper sleep are the most common natural ways of boosting testosterone. You can opt for injection upon advisory from your doctor in order to attain high testosterone levels. This is the recommended remedy for severe testosterone reductions.

What are the effects of low levels of free testosterone?

Low testosterone levels are a common cause of health conditions such as infertility, obesity, fatigue, moodiness, and low libido in men. Hair loss and bone mass loss are also symptoms of low testosterone.

Is free testosterone important?

Free testosterone plays a role in making the bone mass and various body functions. It is also responsible for male development in early puberty. A reduction of this critical hormone may lead to catastrophic failures in the reproductive life of a person. Free testosterone will also increase your overall testosterone levels and help you develop optimal testosterone, which will decrease your risk of developing many health conditions as well as improve the overall quality of your life!

Is the free testosterone test painful?

Testing for testosterone is simple for the patient as the test is conducted on blood drawn from the patient's arm. However, this test might need to be repeated during different intervals to know the actual value of testosterone levels.