Free Testosterone vs. Total Testosterone: Which Number Matters More?
Written by &you Labs Team
Updated
Your test came back "normal." But you still feel every sign of low T. The answer may be hiding in a free testosterone vs total testosterone comparison. A protein called SHBG controls how much stays active. This is why a man can have a normal total number and still feel real low T effects.
Quick answer
Total T measures every bit in your blood. This includes the 98 percent or more that is bound to proteins and inactive. Free T measures only the 1 to 2 percent that is unbound and doing real work. SHBG, short for sex hormone binding globulin, is the main binder. When SHBG runs high, more gets locked up. Less stays active. Total T can look normal while free T is actually low.
Lab testing that's built around you
The three forms testosterone takes in your blood
Form | Share of the total | What it does |
|---|---|---|
Free | 1 to 2 percent | Unbound. Does the real work in your body |
Bound to SHBG | 40 to 60 percent | Tightly locked away. Inactive |
Bound to albumin | 40 to 60 percent | Loosely bound. Still does some work |
Free plus albumin bound together is called bioavailable testosterone. Total testosterone is the sum of all three parts.
Total testosterone
Total T measures everything in your blood, bound or not. It is the standard, most common test. For adult men, the typical range runs from 300 to 1000 ng/dL. Under 300 is generally flagged as low.
This test is cheap and well standardized. It works for most cases. But it has one weakness. It can look normal even when SHBG has locked up most of it. Little may actually be at work in your body.
Free testosterone
Free T measures only the unbound, active part. For adult men, the typical range runs from about 7 to 21 pg/mL. This varies more between labs than the total range does.
This number reflects what your body can actually use. Its main downside is technical. A direct test can be less reliable than a calculated version. Doctors work this out using your total T, SHBG, and albumin together.
SHBG: the protein controlling the balance
SHBG, short for sex hormone binding globulin, is a protein your liver makes. It binds up testosterone and estrogen. This controls how much stays free. Since your liver makes it, it helps to know what healthy ALT and AST levels look like.
What raises SHBG | What lowers SHBG |
|---|---|
Aging | Extra weight, especially around the middle |
An overactive thyroid | Insulin resistance |
Liver disease | Type 2 diabetes |
Certain medicines and estrogen exposure | An underactive thyroid |
The typical adult male range is 10 to 55 nmol/L. A middle range of about 20 to 45 is generally considered ideal.
When total and free testosterone tell different stories
A high SHBG with a normal total T often means one thing. Your free T is actually low, since more is locked away. This is common as men get older. It often comes with real symptoms, despite a "normal" looking number.
A low SHBG with a normal total T means something else. More testosterone is unbound, so your free T may run higher. This is common with extra weight or insulin resistance. It needs a careful reading. It does not always mean things are fine.
A low total T with normal or low SHBG usually means truly low T. Your free T is low too. This is the most straightforward case to diagnose and treat.
Why this actually matters for your care
Picture a man with symptoms and a total T of 350 ng/dL. The real story depends on his SHBG. If SHBG is high, his free T is likely low. This means true low T, despite the "normal" total number. If SHBG is normal, he likely has a low normal, symptomatic result.
This matters even more for older men. SHBG naturally rises with age. Total T alone can hide a real decline. It also matters for men with extra weight or insulin resistance. SHBG often runs low here. This can make total T look artificially low. Addressing weight and metabolic health often helps, before jumping straight to treatment.
Reference range versus optimal range
Marker | Standard reference | Optimal target |
|---|---|---|
Total testosterone | 300 to 1000 ng/dL | 500 to 800 ng/dL |
Free testosterone | About 7 to 21 pg/mL | Upper half of your lab's range |
Bioavailable testosterone | About 100 to 300 ng/dL | Toward the higher end |
Many men sitting in the 300 to 500 ng/dL range still report real symptoms. This technically falls inside "normal."
Signs worth paying attention to
Low T can show up as a lower sex drive. It can mean trouble with erections, and fewer morning erections. It can show up physically too. Watch for lower muscle, more belly fat, weaker bones, and thinner body hair. Mood and focus often take a hit as well. This can mean low motivation, low mood, brain fog, and poor sleep.
When to ask for a free testosterone test
Ask for free T testing in a few cases. One is real symptoms with a "normal" total T. Another is being older and suspecting a real decline. A third is extra weight or insulin resistance, since SHBG can distort the total number here. It is also worth checking if you are tracking an ongoing treatment.
How the test should be done
The best approach checks total T, SHBG, and albumin together. Doctors then calculate your free T from all three. Draw blood in the morning, between 7 and 9 AM, after an overnight fast. Testosterone naturally runs highest then. If the first result looks abnormal, confirm it with a second test. Your doctor may add LH and FSH, two pituitary hormones, to help pinpoint the cause.
Want your total T, SHBG, and free T checked together? Book a &you Labs panel and get a full hormone picture explained by a doctor.
What might be causing it
Testicular causes are marked by high LH and FSH levels. Here, the testicles themselves are not producing enough. Pituitary or brain related causes are marked by low or normal LH and FSH instead. Here, the signal from the brain is weak. This can stem from a pituitary tumor, obesity, or severe illness. A third group is lifestyle related. Extra weight, insulin resistance, poor sleep, high stress, and very heavy exercise can all suppress T, with no structural cause at all. Learn more about the different root causes in our male hypogonadism guide.
What treatment can look like
For a lifestyle related cause, addressing weight, sleep, and stress often raises T on its own. This can be by 20 to 30 percent in men who lose real weight. A true diagnosis needs a low result confirmed on two separate mornings. It also needs a look into the underlying cause. Testosterone replacement therapy is an option for confirmed, symptomatic cases. It comes in several forms. Regular checks follow, on free T, red blood cell count, and prostate health. It is not right for a normal T level. It is not a shortcut to try casually. Some cases call for other medicines instead. These support your body's own production, rather than replacing it.
Frequently asked questions
Should I get total or free testosterone tested?
Ideally both. Total testosterone paired with SHBG gives the fullest picture. Doctors use these to calculate free testosterone. A direct free testosterone test alone has some technical limits.
Is free testosterone the more important number?
Often, yes. This is especially true for older men, men with extra weight, and men with metabolic issues. Total testosterone is still a reasonable starting point.
What counts as a "normal" free testosterone?
Reference ranges vary a lot between labs. Generally, the upper half of your lab's range is a healthy target for an adult man.
Can lifestyle changes actually raise my testosterone?
Yes, for many men. Weight loss alone can raise total testosterone by 20 to 30 percent in men carrying significant extra weight.
Is testosterone replacement therapy safe?
For a confirmed, symptomatic diagnosis, generally yes, with proper monitoring. It is not right for a normal testosterone level. It is not a general performance boost either.
Lab testing that's built around you
Key takeaways
- Total testosterone measures everything in your blood. Free testosterone measures only the small active share.
- SHBG can make total testosterone look normal while free testosterone is actually low.
- For symptomatic men, a calculated free testosterone, using total testosterone plus SHBG, is the more reliable number.
- Older men and men with extra weight or metabolic issues benefit most from a full evaluation.
- Lifestyle change, addressing weight, sleep, and exercise, often helps functional low testosterone before medicine is needed.
Ready to check your full hormone picture? Book your &you Labs panel. Your results come back with both the standard range and the healthy target range, plus a doctor's written interpretation.
The &you Labs Team combines medical science with personal care. We help Filipinos understand their health markers with blood work analysis that is easy to follow, whole person support, and health expertise built for Filipino life.
This content is provided for educational purposes only and is not intended as medical advice. It should not replace professional medical consultation, diagnosis, or treatment. Please consult a qualified healthcare provider to discuss the risks and benefits of any treatment option.
