Free vs total testosterone: what each measures and when it matters
Most testosterone reports show a total number. Some also show free testosterone. The two answer slightly different questions, and for many men the total number is enough. This page explains the difference and when free testosterone is worth checking.
Free and total testosterone
Free and total testosterone on one order, so you get both numbers from one draw.
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What each test measures
MedlinePlus says all the testosterone in your blood is either bound to proteins or unbound (free). Free testosterone is more available for your body to use. Most testosterone is bound to proteins such as sex hormone-binding globulin (SHBG) and albumin, and bound testosterone is not as easily used.
The Endocrine Society guideline gives the split: only about 2 to 4 percent of circulating testosterone is unbound.
| Total testosterone | Free testosterone | |
|---|---|---|
| What it counts | Bound and unbound testosterone | Unbound testosterone only |
| How common | The most common test, per MedlinePlus | Less common, per MedlinePlus |
| How it is obtained | Measured in a blood sample | Measured directly, or calculated from other results |
| Reference ranges | The guideline cites a harmonized lower limit for CDC-certified assays | The guideline says no harmonized range exists |
Why the two can disagree
Total testosterone includes the part held by SHBG. When SHBG changes, total can move without free testosterone moving with it. The guideline’s diagnostic chart notes that total testosterone may be high in some conditions where SHBG is high, such as HIV, so a total result can overstate how much hormone is unbound. That is why the guideline asks for free testosterone in some cases.
A reference laboratory’s catalog makes the same point. It says free and bioavailable levels usually parallel total, but conditions and medicines that change SHBG can shift total testosterone without necessarily shifting free testosterone, or the other way round.
When checking free testosterone makes sense
The Endocrine Society guideline recommends measuring free testosterone in these situations:
- Total testosterone is at or near the lower limit of normal. The guideline gives roughly 200 to 400 ng/dL as the borderline zone.
- A condition lowers SHBG. Its list includes obesity, diabetes, hypothyroidism, acromegaly, nephrotic syndrome and use of glucocorticoids.
- A condition raises SHBG. Its list includes aging, HIV disease, cirrhosis and hepatitis, hyperthyroidism, use of some anticonvulsants and use of estrogens.
If none of these applies and you want a baseline, total testosterone is a reasonable first step. If you are unsure, the test finder can help. If one applies, the free and total test gives you both numbers on one order. If you already have total and SHBG results, you can enter both in the free testosterone calculator.
The seller offers total only, free only, or both on one order:
- Total testosteroneTotal testosterone only $49 See this test at HealthLabs
- Free testosteroneFree testosterone only $59 See this test at HealthLabs
- Free and total testosteroneBoth numbers on one order $99 See this test at HealthLabs
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How free testosterone is measured
The Endocrine Society guideline describes three ways to get a free testosterone value: equilibrium dialysis, a formula that uses total testosterone, SHBG and albumin, and direct analog immunoassays, and it recommends against the last.
A calculated value needs SHBG and albumin results as well as total testosterone. SHBG is a separate marker. See SHBG. The free testosterone calculator estimates free testosterone from total testosterone and SHBG with a published formula, and assumes a typical albumin level unless you enter your own. It is an estimate, not a lab result. See test names on lab orders for how free testosterone tests are named.
Reference ranges differ
Because there is no harmonized reference range for free testosterone, the guideline says ranges vary considerably by the dialysis method or formula used. Until a harmonized range exists, it says the lower limit set by your own laboratory may be used. A reference laboratory’s catalog, for example, lists free testosterone in ng/dL by age band, while the guideline quotes a research threshold in pg/mL.
Use the range printed on your own report. For published ranges with sources, see free testosterone levels.
What neither test tells you
Neither number diagnoses anything. MedlinePlus says abnormal results with symptoms may signal a problem, and that results mean different things depending on the test, your age, your symptoms and other tests. The guideline calls for symptoms and consistently low results before a diagnosis, usually confirmed on a repeat morning sample. See retesting.
If you have symptoms, or your two numbers disagree and you are unsure why, see a clinician.
Free and total testosterone
$99
See this test at HealthLabsPrice checked October 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.
Keep reading
- Testosterone test guide: which test to get, what it shows, how to order
Which testosterone blood test to choose, what total and free results show, when to draw, how ordering works and what to do with the result.
- What is free testosterone? A plain-language definition
Free testosterone is the part of your testosterone not bound to proteins. Learn why it is measured, how it differs from total, and what it can't show.
- Testosterone lab test names on orders and results, decoded
What 'total', 'free', 'free direct', 'bioavailable' and method labels like LC-MS/MS mean on a testosterone lab order or result, and how to read the units.