Enter the Total Testosterone, Sex Hormone Binding Globulin, and Albumin into the calculator to determine the Free Testosterone Level. This calculator can also evaluate any of the variables given the others are known.

Free Testosterone Level Formula

The following formula is used to calculate the Free Testosterone Level.

FTL = (TT * SHBG) / (Albumin + SHBG)


  • FTL is the Free Testosterone Level TT is the Total Testosterone SHBG is the Sex Hormone Binding Globulin Albumin is a protein that binds to testosterone

To calculate the Free Testosterone Level, multiply the Total Testosterone by the Sex Hormone Binding Globulin. Then, add the Albumin to the Sex Hormone Binding Globulin. Divide the first result by the second result to get the Free Testosterone Level.

What is a Free Testosterone Level?

A Free Testosterone Level is a medical test that measures the amount of testosterone (a male sex hormone) that is not bound to proteins in the blood. This is important because most testosterone is bound to sex hormone-binding globulin (SHBG) or albumin, and only a small portion is “free” or unbound. This free testosterone is biologically active and can affect the body’s tissues. The test is often used to diagnose sexual health issues in men, such as erectile dysfunction, infertility, or low sex drive, which may be caused by low testosterone levels.

How to Calculate Free Testosterone Level?

The following steps outline how to calculate the Free Testosterone Level (FTL) using the given formula:

  1. First, determine the value of Total Testosterone (TT).
  2. Next, determine the value of Sex Hormone Binding Globulin (SHBG).
  3. Next, determine the value of Albumin.
  4. Using the formula FTL = (TT * SHBG) / (Albumin + SHBG), substitute the values of TT, SHBG, and Albumin into the formula.
  5. Finally, calculate the Free Testosterone Level (FTL).
  6. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge:

Total Testosterone (TT) = 500

Sex Hormone Binding Globulin (SHBG) = 20

Albumin = 10