Understand Percent Free PSA (% Free PSA)

Percent Free PSA (% Free PSA)

Hormone markers

What the test generally measures, and what to ask about it.

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Updated Jul 13, 2026

What is Percent Free PSA (% Free PSA)?

The share of your total PSA that is in the unbound (free) form, used to help judge the chance that an elevated PSA is due to cancer.

Percent-free PSA is a calculation, free PSA divided by total PSA expressed as a percentage, used mainly in men who already have an elevated total PSA. A lower percentage can be associated with a higher chance that prostate cancer is present, which can help a man and his doctor decide whether to proceed to biopsy. It is a supporting piece of information, not a diagnosis, and applies only to men. Because it depends on two other measurements, it is always interpreted together with the total and free PSA values and the overall clinical picture.

This glossary entry is for informational purposes only and is not a substitute for professional medical advice. Read our Terms of Use.

References

Clinical "Prostate-specific antigen (PSA) blood test" MedlinePlus Medical Encyclopedia (NIH/NLM). medlineplus.gov/ency/article/003346.htm.

"Prostate-Specific Antigen (PSA) Test" National Cancer Institute (NIH). www.cancer.gov/types/prostate/psa-fact-sheet.

About our sources

Official sources

Government health agencies, national institutes, and intergovernmental bodies whose guidelines carry regulatory or policy weight.

MedlinePlus (NIH / U.S. National Library of Medicine) NIH Office of Dietary Supplements World Health Organization Centers for Disease Control and Prevention NCBI Bookshelf / StatPearls (NIH/NLM) NHLBI, National Institutes of Health NIDDK, National Institutes of Health National Cancer Institute (NIH) National Health Service (UK) National Institute for Health and Care Excellence European Food Safety Authority

Clinical / professional

Medical societies, specialty colleges, and professional associations whose consensus statements reflect clinical practice standards.

Testing.com / Lab Tests Online (ADLM, ex-AACC) Mayo Clinic Laboratories Cleveland Clinic MSD Manuals American Diabetes Association American Heart Association Endocrine Society American Thyroid Association

Peer-reviewed research

Original research articles and systematic reviews published in indexed journals and verified through PubMed or DOI.

History of updates

Published · Jul 13, 2026

First published; written and independently fact-checked against the cited sources.

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