What is free testosterone and why is it the more important number?
Free testosterone is the fraction of circulating testosterone that is not bound to SHBG and is biologically available to tissues. It is frequently the more clinically meaningful number, because two men with identical total testosterone can have very different free testosterone depending on SHBG.
Full answer
Total testosterone measures every testosterone molecule in circulation — bound and unbound. Free testosterone measures only the fraction that is unbound to SHBG and freely available to receptors. It is often the more clinically meaningful read, particularly when SHBG is high or low. A man with total testosterone of 600 ng/dL and high SHBG can be symptomatically deficient, while another with total of 450 ng/dL and low SHBG can be symptomatically sufficient. The oMeds panel reads total testosterone, free testosterone (calculated and, where indicated, direct), and SHBG together so the provider can interpret the bioavailable fraction rather than the gross total. Symptoms, body composition, sleep, and cardiovascular context anchor the read; the number alone never does.
Educational. Not a substitute for individualized provider review.
- Testosterone optimization pathway — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29