Total vs. Free Testosterone Tests: What’s The Difference?

By Dr. Diana Rangaves

Total vs. Free Testosterone Tests: What’s The Difference?

This is the question that often arises when lab results do not match how someone feels. On paper, testosterone levels may appear normal, yet symptoms of low testosterone, such as fatigue, low mood, or reduced strength, persist. That gap leads many to wonder whether total testosterone tells the full story, or if free testosterone is the missing piece.

The truth is, both tests matter, but they do not mean the same thing. Looking at only one without the other can cause you to miss important insights about your hormones, your health, and even your day-to-day well-being.

This article will break down the differences between total and free testosterone, explain why both tests exist, and explain when each one is truly relevant.

What Is Total Testosterone?

Total testosterone is the sum of all the testosterone circulating in the bloodstream, most of which is bound to proteins. A large portion attaches to sex hormone binding globulin (SHBG), which locks it away so the body cannot use it. Another portion binds more loosely to albumin, and some of that can be released when needed. The rest, a small 1-3%, remains unbound and that is what we call free testosterone.

Since total testosterone reflects the body’s overall production, it is often the first number healthcare providers examine when evaluating hormone health. A normal total level does not always mean the body has enough usable testosterone. That is why understanding free testosterone becomes so important.

What Is Free Testosterone?

Free testosterone is the small fraction of testosterone that is not bound to SHBG or albumin. Since it is unbound, it can freely enter tissues and exert its effects, ranging from supporting muscle growth to influencing mood and sexual health.

Testing free testosterone is less common than testing total testosterone. Many routine blood panels only measure the total amount, while free testosterone often requires either a direct test or a calculation using total testosterone and SHBG levels. Despite being less commonly reported, it is often the number that explains why some people experience symptoms even when their total testosterone looks “normal.”

Key Differences Between Total And Free Testosterone Tests

What They Measure

Total testosterone represents the sum of everything circulating in the blood, both the portion bound to proteins and the small amount that is free. Free testosterone, on the other hand, focuses only on the fraction that is unbound and immediately available for the body to use. In practice, this means total testosterone tells you how much is present, while free testosterone tells you how much is actually active.

How They Are Influenced

Protein levels, particularly SHBG, can significantly influence total testosterone levels. For example, someone with high SHBG may show a normal total testosterone result, even though their free testosterone is well below what it should be. Free testosterone cuts through that by showing the actual usable amount, giving a more accurate reflection of hormone activity in cases where SHBG is out of balance.

Testing Methods

Measuring total testosterone is straightforward. It is inexpensive, widely available, and often included in standard blood panels. Free testosterone is more complex. Some labs use a direct test, while others calculate it from total testosterone, SHBG, and albumin. The most accurate option, equilibrium dialysis, is not commonly available in routine practice. This difference in testing makes total testosterone the easier starting point, but free testosterone is the more precise measure when symptoms and lab numbers do not align.

Clinical Usefulness

Total testosterone is most valuable as a screening tool. It can reveal whether overall hormone production is low or high. Free testosterone becomes more useful when the clinical picture is less clear. For example, a person may have symptoms of low T despite having a “normal” total level. By looking at free testosterone, healthcare providers can understand whether there is enough active hormone available to explain how the patient feels.

When to Test Total Testosterone and When to Test Free Testosterone

Both tests provide valuable information, but they are not used in the same situations. Total testosterone is usually the first step. It gives a broad sense of how much hormone the body is producing and is included in most standard lab panels. Free testosterone testing comes in when the picture is not clear, for instance, when symptoms suggest low T but the total number looks fine, or when other factors may be affecting how much testosterone is actually active.

Routine Screening

For most people, total testosterone is the right place to start. It is simple, inexpensive, and offers a reliable overview of hormone production. Healthcare providers often order it during routine checkups or when patients first report possible low T symptoms.

When Symptoms and Lab Results Don’t Match

Some people have normal total testosterone but still feel tired, irritable, or have a low libido. This often happens when SHBG is high, binding up much of the hormone. In these cases, free testosterone helps explain the gap between the lab result and the way a person feels.

Special Situations

Free testosterone is especially valuable in certain groups. In men with obesity or metabolic syndrome, SHBG levels may be low, which can make total testosterone appear misleadingly low even if free testosterone is adequate. In older men, SHBG levels often rise, so free testosterone can reveal deficiencies that a total test might miss. In women, where testosterone levels are naturally much lower, free testosterone can also be a better indicator of imbalance than total testosterone alone.

Taking the Next Step in Testosterone Testing

Total testosterone gives the big picture, while free testosterone shows what is active. Looking at both together often explains symptoms that one test alone might miss.

If you want an easy way to check your levels, Everlywell offers at-home testosterone testing with physician-reviewed results you can share with your healthcare provider. It is a simple first step toward understanding your hormone health.

References

1. Low testosterone (Male hypogonadism). Cleveland Clinic. Published July 15, 2025. Accessed September 6th, 2025 https://my.clevelandclinic.org/health/diseases/15603-low-testosterone-male-hypogonadism.

2. Testosterone levels test. Accessed September 6th, 2025. https://medlineplus.gov/lab-tests/testosterone-levels-test/#:~:text=A%20total%20testosterone%20test%2C%20which,provider%20diagnose%20certain%20medical%20conditions

3. SHBG blood test. Accessed September 6th, 2025. https://medlineplus.gov/lab-tests/shbg-blood-test/.

4. Kacker R, Hornstein A, Morgentaler A. Free testosterone by direct and calculated measurement versus equilibrium dialysis in a clinical population. The Aging Male. 2013;16(4):164-168. Accessed September 6th, 2025. doi:10.3109/13685538.2013.835800

5. Rosner W, Auchus RJ, Azziz R, Sluss PM, Raff H. Utility, limitations, and pitfalls in measuring testosterone: an Endocrine Society position statement. The Journal of Clinical Endocrinology & Metabolism. 2007;92(2):405-13. doi.org/10.1210/jc.2006-1864 https://academic.oup.com/jcem/article-abstract/92/2/405/2566757