Last updated: June 2026 · Reviewed June 2026 · Built by the InjectBuddy team
What Is Total Testosterone? Ranges & units, decoded
Total testosterone is the sum of every testosterone molecule in your blood sample — both the part bound to carrier proteins and the small free fraction your tissues can actually use. It is the headline figure a doctor reads first, reported in ng/dL in the US or nmol/L elsewhere, and a normal result does not rule out a low free fraction when SHBG is elevated. This guide explains what the total number counts, how it splits into bound and free fractions, what typical ranges look like, how the unit conversion works, and answers the questions people ask most.
- Total = bound + free. Roughly 97–99% of testosterone rides on SHBG or albumin; only about 1–3% floats free.
- Typical male range: labs usually print ~300–1000 ng/dL (~10.4–34.7 nmol/L); the harmonized research range for healthy young men is 264–916 ng/dL.
- Two unit systems: divide ng/dL by 28.85 to get nmol/L; multiply nmol/L by 28.85 to go back.
- Total alone can mislead. A normal total with high SHBG can still leave a low free fraction — estimate it with the free testosterone index calculator.
What the number actually counts
When a lab measures total testosterone, it does not separate the hormone by what it is attached to. It measures everything in the tube: the testosterone tightly bound to sex hormone-binding globulin (SHBG), the testosterone loosely bound to albumin, and the tiny unbound fraction. Picture a car park where most spaces are taken by long-term permit holders (SHBG), some by short-stay visitors who come and go easily (albumin), and only a handful of cars are circling freely looking for a tissue to act on (free testosterone). Total testosterone is the full headcount of cars; it does not tell you how many are actually free to drive away.
That distinction matters because tissues only respond to the unbound and loosely-bound hormone. Most circulating testosterone is bound to plasma proteins, while the small free fraction acts at the tissue level (StatPearls, Physiology, Testosterone). So total testosterone is a starting point: a high total is reassuring, but the binding proteins decide how much is usable.
Bound vs free: the split inside one number
As a rule of thumb, of all the testosterone in a total result, around 40–50% is bound to SHBG, around 50–60% is bound to albumin, and only about 1–3% is truly free. Bioavailable testosterone — free plus the easily-released albumin-bound portion — is what clinicians watch when symptoms and total testosterone disagree.
Total testosterone reads 600 ng/dL. If free testosterone is ~2% of total, the free portion is 600 × 0.02 = 12 ng/dL, which equals 120 ng/L or about 1.2 nmol/L. The other 588 ng/dL is bound to proteins and held in reserve.
Two men both show 500 ng/dL total. Man A has normal SHBG and ~2.2% free (~11 ng/dL). Man B has high SHBG and only ~1.2% free (~6 ng/dL). Identical totals, but Man B's tissues see roughly half the usable hormone — the total number alone hid the gap.
Typical total testosterone ranges by age and unit
Reference ranges vary by lab and assay, so always compare your result to the range printed on your own report. As a guide, the table below pairs commonly cited adult-male ranges with their nmol/L equivalents, including the harmonized research range from a four-cohort study of more than 9,000 men (Travison et al., 2017).
| Group / source | Total T (ng/dL) | Total T (nmol/L) |
|---|---|---|
| Typical lab male range | 300–1000 | 10.4–34.7 |
| Harmonized, men 19–39 | 264–916 | 9.2–31.8 |
| Median, healthy young men | 531 | 18.4 |
| Common low threshold | <300 | <10.4 |
| Adult women (reference) | 15–70 | 0.5–2.4 |
Guidelines diagnose low testosterone from symptoms plus a genuinely low morning level, not from a single borderline number. StatPearls notes hypogonadism is usually flagged when a morning serum testosterone is below 300 ng/dL on at least two occasions, while the Endocrine Society stresses a fasting morning draw with an accurate assay and a repeat confirmation (Bhasin et al., 2018).
Units: ng/dL and nmol/L
Two unit systems describe the same hormone. The US and several other countries report ng/dL (mass per volume); much of the world reports nmol/L (moles per volume). The conversion factor is fixed by testosterone's molar mass: 1 nmol/L = 28.85 ng/dL. To read a foreign report, divide ng/dL by 28.85, or multiply nmol/L by 28.85.
A US report shows 720 ng/dL. Divide by 28.85: 720 / 28.85 = 24.9 nmol/L. That sits comfortably inside the typical male range.
A UK report shows 11 nmol/L. Multiply by 28.85: 11 × 28.85 = 317 ng/dL. Just above the common 300 ng/dL low threshold — borderline, not clearly low.
Getting the unit wrong is the most common total-testosterone misreading. A result of "20" is healthy in nmol/L but absurd in ng/dL, so the label matters as much as the digits. For a deeper walkthrough, see testosterone units explained: nmol/L vs ng/dL.
How this is calculated: total feeding free T
You cannot measure free testosterone directly from a total number, but you can estimate it. The widely used Vermeulen method takes total testosterone, SHBG, and albumin and solves the binding equations to estimate free and bioavailable testosterone (Vermeulen et al., 1999). The total is the raw material; SHBG and albumin decide how much of it stays free. A simpler screening figure, the Free Androgen Index (FAI), divides total testosterone by SHBG and multiplies by 100.
Total testosterone 18 nmol/L, SHBG 30 nmol/L. FAI = (18 / 30) × 100 = 60. A typical male FAI sits around 35–100, so 60 is mid-range despite needing the SHBG number to interpret it.
Total 18 nmol/L with SHBG 60 nmol/L gives FAI = (18 / 60) × 100 = 30 — half the previous result from the same total. Same headline number, very different usable hormone.
A US total of 550 ng/dL with SHBG reported as 35 nmol/L needs matching units first. Convert: 550 / 28.85 = 19.1 nmol/L, then FAI = (19.1 / 35) × 100 = 55. Mixing ng/dL with nmol/L here would give nonsense.
Common ways total testosterone is misread
The first trap is treating total as the whole story. A reassuring total with high SHBG can still leave symptoms unexplained, which is why guidelines add a free or bioavailable estimate when the total sits near the lower limit (Bhasin et al., 2018). The second trap is timing: testosterone peaks in the early morning and drifts down through the day, so an afternoon draw can read falsely low. The third is the unit slip covered above — always read the label, not just the digits.
A morning draw reads 540 ng/dL; an afternoon repeat on the same man reads ~430 ng/dL. Neither is wrong, but only the fasting morning value should be compared to the reference range and confirmed on a second day.
This page explains what the number means and how the arithmetic works. It does not diagnose anything or replace your prescriber — treatment decisions belong to a qualified clinician reading your full picture.
So, what is total testosterone?
Total testosterone is the combined count of every testosterone molecule in a blood sample — SHBG-bound, albumin-bound, and the small free fraction — reported in ng/dL or nmol/L depending on the country. It is the starting point for evaluating testosterone status, but a normal total does not guarantee normal usable hormone, because high SHBG can lock up most of it. To see how much is actually free, divide your total by your SHBG and multiply by 100 (the Free Androgen Index), or use the free testosterone index calculator to run the full Vermeulen estimate with your own numbers.
FAQs
What is total testosterone?
What is a normal total testosterone level?
Is total testosterone the same as free testosterone?
How do I convert ng/dL to nmol/L?
Why does my total testosterone change between tests?
Sources
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018. PubMed PMID: 29562364.
- Travison TG, et al. Harmonized Reference Ranges for Circulating Testosterone Levels in Men of Four Cohort Studies in the US and Europe. J Clin Endocrinol Metab. 2017. PubMed PMID: 28324103.
- Sizar O, Leslie SW, Schwartz J. Male Hypogonadism. StatPearls. NCBI Bookshelf NBK532933.
- StatPearls. Physiology, Testosterone. NCBI Bookshelf NBK526128.
- Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Clin Endocrinol Metab. 1999. PubMed PMID: 10523012.
This guide is for general educational purposes only and does not constitute medical advice. Total testosterone reference ranges vary by lab and assay; always interpret your result with the range on your own report and your prescriber's guidance.