A healthy premenopausal woman typically has a free testosterone level between 1.2 and 6.4 pg/mL (picograms per milliliter). That range comes from a large study of normally cycling women aged 18 to 49, with the midpoint estimated for a 30-year-old. Your ideal number within that range depends on your age, your body’s production of a key binding protein, and whether you’re pre- or postmenopausal.
What Free Testosterone Actually Measures
Most of the testosterone circulating in your blood is bound to proteins, particularly one made by the liver called sex hormone binding globulin (SHBG). Bound testosterone is essentially inactive. It can’t interact with your tissues or do any of the things testosterone is supposed to do, like support bone density, muscle mass, energy, and sex drive.
Free testosterone is the small unbound fraction that’s available to work in your body. In women, total testosterone normally falls between about 15 and 46 ng/dL, but only a tiny slice of that is free. Measuring free testosterone gives a more precise picture of how much hormone your tissues are actually using, which is why it often shows up on lab orders alongside total testosterone.
How SHBG Shifts Your Numbers
Because SHBG controls how much testosterone stays locked up versus how much roams free, anything that raises or lowers SHBG will change your free testosterone level even if your body is producing the same total amount. Birth control pills, for example, significantly increase SHBG, which can push free testosterone down. Insulin resistance and obesity tend to lower SHBG, which lets more testosterone circulate freely.
This matters when you’re reading lab results. Two women can have the same total testosterone but very different free testosterone levels based on their SHBG. If your SHBG is unusually high, your tissues may not be getting enough testosterone even though your total level looks normal. If SHBG is low, more testosterone is active in your body, sometimes producing symptoms of excess like acne or unwanted hair growth.
Levels That Suggest Deficiency
There’s no universally agreed-upon cutoff for “too low,” but clinical guidelines from Boston University’s sexual medicine program offer useful thresholds. For women under 50, a free testosterone level below 1.5 pg/mL suggests androgen deficiency. For women 50 and older, the threshold drops to below 1.0 pg/mL. Values even slightly above those numbers are considered borderline, especially if symptoms are present.
The symptoms that typically accompany low free testosterone include reduced sex drive, persistent fatigue, loss of muscle tone, and low mood. A study of premenopausal and postmenopausal women who reported decreased libido found they also had measurably lower total and free testosterone compared to women without those complaints. Total testosterone below 25 ng/dL in women under 50, or below 20 ng/dL in women 50 and older, is another marker clinicians use alongside the free testosterone reading.
Levels That Signal Excess
On the high end, elevated free testosterone is one of the hallmarks of polycystic ovary syndrome (PCOS), the most common hormonal disorder in women of reproductive age. PCOS-related testosterone elevations are usually moderate. Most women with PCOS have a total testosterone at or below 150 ng/dL. When total testosterone reaches 200 ng/dL or higher, that’s a red flag for something more serious, like an ovarian or adrenal tumor, and warrants further investigation.
Symptoms of excess testosterone in women include irregular periods, acne along the jawline and chin, thinning hair on the scalp, increased body or facial hair, and difficulty losing weight. Because SHBG plays such a large role, some women develop these symptoms with a normal-looking total testosterone simply because their free fraction is elevated.
Why Testing Methods Matter
Not all free testosterone tests are created equal, and this is worth knowing before you interpret your results. The gold standard method, called equilibrium dialysis, directly measures the unbound hormone. Many labs instead use a calculation that estimates free testosterone from your total testosterone and SHBG levels. A study comparing these approaches found that at least 25% of calculated results deviated significantly from the gold standard, with the worst accuracy in women who had high SHBG levels.
This means a calculated free testosterone result can be misleading, particularly if you’re on hormonal birth control or have another reason for elevated SHBG. If your results don’t match your symptoms, it’s reasonable to ask whether the lab used a direct measurement or a calculation. Some clinicians prefer to rely on total testosterone for this reason, noting it tends to be more reliable across different lab methods.
What Changes With Age and Menopause
Testosterone production in women peaks in the early 20s and declines gradually from there. By the time you reach your 40s, your levels may be roughly half what they were at 20. Menopause doesn’t cause a sudden testosterone drop the way it does with estrogen, but the steady decline means postmenopausal women generally have lower free testosterone than younger women. The lower deficiency threshold for women over 50 (1.0 pg/mL versus 1.5 pg/mL) reflects this natural age-related decrease.
Surgical menopause, where both ovaries are removed, is a different story. The ovaries produce about half of a woman’s testosterone, so removing them can cause a sharp and immediate drop. Women who’ve had this surgery often experience more pronounced symptoms of testosterone deficiency than women who go through natural menopause.
Getting an Accurate Reading
Testosterone levels fluctuate throughout the day and across your menstrual cycle. For the most consistent results, blood draws are best done in the morning, when testosterone peaks. If you’re still cycling, testing during the first few days of your period gives the most stable baseline. Fasting isn’t typically required, but it’s worth confirming with the ordering provider.
If your results come back outside the normal range, a single test isn’t usually enough for a diagnosis. Repeat testing, ideally with the same lab and method, helps confirm whether the reading reflects a true pattern or just normal day-to-day variation. Pairing free testosterone with total testosterone and SHBG gives the most complete picture of what’s actually happening hormonally.