Free Testosterone Unit Converter
Convert between SI and conventional units. Enter any value — all other fields update instantly.
* The SI units is the recommended method of reporting clinical laboratory results
Convert pmol/L, pg/mL, pg/dL, pg/L, and ng/L Instantly
Understanding your testosterone results can be genuinely confusing. You get a lab report, and the number means nothing to you. Or worse, you search for reference ranges online and find them in completely different units than what's on your report. That's not your fault — laboratories around the world use different measurement systems, and the same hormone level can look wildly different depending on which unit is being used.
This free testosterone converter solves that problem instantly. Enter any value in any unit, and every other unit updates automatically. No formulas, no manual math, no guessing.
What Is Free Testosterone?
Testosterone is the primary male sex hormone, though it plays important roles in women too. Most people have heard of it. But the term "free testosterone" is more specific — and more clinically meaningful.
Most testosterone in your bloodstream doesn't float around freely. About 60% binds tightly to a protein called sex hormone-binding globulin (SHBG), and another 38% attaches loosely to albumin. Only 1–5% remains truly unbound. That small fraction is free testosterone — and it's the portion your cells can actually use.
Free testosterone is biologically active. It crosses cell membranes, binds to receptors, and triggers the hormonal effects that testosterone is known for. Bound testosterone, by contrast, is largely inactive. This is why many clinicians consider free testosterone a more accurate indicator of hormonal status than total testosterone alone — especially in people with abnormal SHBG levels, which shift how much of the total is actually available.
Why Are There So Many Units?
This is the question that trips everyone up. A result of 3.46 pg/mL and a result of 12 pmol/L describe the exact same testosterone level. They're identical. The number changes because the units measure concentration differently.
Different countries and different laboratory systems adopted different standards over time. The SI system (Système International) uses molar concentration — pmol/L — which tells you how many molecules of the hormone are present per litre of blood. Conventional units, more common in the United States, express mass concentration — pg/mL, pg/dL, and similar variants.
Neither system is wrong. They just measure the same thing from different angles, the way you can describe someone's height in feet or centimetres. The conversion between them depends on the molecular weight of the substance being measured. For free testosterone, the molecular weight is 288.42 g/mol. That single number is the key to every conversion on this page.
Units This Calculator Converts
pmol/L — Picomoles per litre. The SI unit, now recommended globally for reporting clinical laboratory results. Common in Europe, Canada, and Australia.
pg/mL — Picograms per millilitre. The most widely used conventional unit in the United States. Most US reference ranges are published in pg/mL.
pg/dL — Picograms per decilitre. One decilitre is 100 millilitres, so pg/dL values are 100 times larger than pg/mL for the same concentration.
pg/100mL — Picograms per 100 millilitres. Numerically identical to pg/dL. Older literature and some reference tables use this notation interchangeably.
pg% — Picograms percent. Also numerically identical to pg/dL and pg/100mL. The "%" refers to per 100 mL, not a percentage in the everyday sense.
pg/L — Picograms per litre. Since a litre is 1,000 millilitres, pg/L values are 1,000 times larger than pg/mL values. This unit appears in some research publications.
ng/L — Nanograms per litre. Numerically the same as pg/mL, because 1 ng/L = 1 pg/mL. Some laboratory systems report in ng/L when pg/mL might cause confusion with other tests.
How to Use This Converter
It's simple. Type any value into any field and every other field fills in automatically.
If your lab report shows 3.5 pg/mL, type 3.5 into the pg/mL box. The converter immediately shows the equivalent in pmol/L, pg/dL, pg/L, and every other unit.
If you're reading a research paper that uses pmol/L and your doctor's reference range is in pg/mL, enter the pmol/L value and read off the pg/mL result.
There is no preferred direction. The converter works from any unit to all others simultaneously. That's the point — you should never have to hunt for a starting unit or work through conversion steps manually.
Reference Ranges for Free Testosterone
Reference ranges vary between laboratories, measurement methods, and populations. Always compare your result against the ranges provided by the specific laboratory that processed your test. That said, widely cited general ranges give useful context.
In adult men, free testosterone typically ranges from roughly 5 to 21 pg/mL (approximately 17 to 73 pmol/L), with levels peaking in the morning and declining through the day. Values decline gradually with age from the third decade onward.
In adult women, free testosterone is substantially lower — typically around 0.1 to 6.4 pg/mL (approximately 0.3 to 22 pmol/L). Values vary across the menstrual cycle and shift significantly during pregnancy and menopause.
Children have very low free testosterone levels, rising substantially during puberty under the influence of gonadotropin-stimulating hormones from the pituitary.
When Is Free Testosterone Tested?
Doctors measure free testosterone in a range of clinical situations. In men, the test helps evaluate symptoms of low testosterone — fatigue, reduced libido, erectile dysfunction, loss of muscle mass, mood changes, and thinning hair. It's also used to investigate infertility, delayed or early puberty, and to monitor men receiving testosterone replacement therapy.
In women, free testosterone measurement helps diagnose and manage conditions involving hormonal imbalance. Elevated levels may point to polycystic ovarian syndrome (PCOS), adrenal gland disorders, ovarian or adrenal tumors, or congenital adrenal hyperplasia. Low levels in women are associated with reduced energy, low libido, and in some cases, diminished bone density.
Because SHBG levels are strongly influenced by conditions like obesity, liver disease, thyroid disorders, and insulin resistance, total testosterone alone can give misleading results. A patient with low SHBG may have a low total testosterone but a completely normal or even elevated free fraction. Measuring free testosterone directly captures what total testosterone misses.
A Note on Measurement Methods
Free testosterone is notoriously difficult to measure accurately. The gold standard is equilibrium dialysis, but this method is expensive, time-consuming, and not widely available. Many laboratories use calculated free testosterone — derived from total testosterone, SHBG, and albumin — which is accurate enough for most clinical decisions. Direct immunoassay methods also exist but tend to be less reliable at the low concentrations typical in women and children.
When comparing results across different tests or laboratories, be aware that the measurement method matters, not just the unit. Two results in the same unit from different labs using different methods may not be directly comparable.
