TRT lab reference ranges and unit conversion table
Total testosterone converts from ng/dL to nmol/L by multiplying by 0.0347, and back by multiplying by 28.8. Estradiol converts from pg/mL to pmol/L by multiplying by 3.671. Adult male total testosterone is commonly reported as 300–1,000 ng/dL (10.4–34.7 nmol/L), with roughly 300 ng/dL used as the diagnostic threshold on a confirmed morning sample.
The ranges here are orientation figures from published guidelines. Your own report's range is derived from that laboratory's assay and population and is the one that applies to your result. This page is educational reference, not medical advice.
Why this conversion table exists
Testosterone results are reported in ng/dL in the United States and nmol/L almost everywhere else. Someone comparing a US forum post to a UK blood panel is comparing numbers that differ by a factor of nearly 29 — which is how a perfectly ordinary 18 nmol/L gets mistaken for a catastrophic 18 ng/dL.
Below are the conversion factors for the markers that actually appear on a testosterone panel, followed by the reference intervals commonly used for adult men and the guideline positions behind the clinically important thresholds.
Unit conversion factors
| Marker | Conventional unit | SI unit | Conventional → SI | SI → conventional |
|---|---|---|---|---|
| Total testosterone | ng/dL | nmol/L | × 0.0347 | × 28.8 |
| Free testosterone | pg/mL | pmol/L | × 3.47 | × 0.288 |
| Estradiol (E2) | pg/mL | pmol/L | × 3.671 | × 0.272 |
| SHBG | nmol/L | nmol/L | same unit | same unit |
| LH / FSH | mIU/mL | IU/L | × 1 (equivalent) | × 1 (equivalent) |
| Prolactin | ng/mL | mIU/L | × 21.2 | × 0.047 |
| DHEA-S | µg/dL | µmol/L | × 0.0271 | × 36.9 |
| Hemoglobin | g/dL | g/L | × 10 | × 0.1 |
| PSA | ng/mL | µg/L | × 1 (equivalent) | × 1 (equivalent) |
| Albumin | g/dL | g/L | × 10 | × 0.1 |
Adult male reference intervals
| Marker | Typical adult male range (conventional) | Same range in SI | Notes |
|---|---|---|---|
| Total testosterone | 300–1,000 ng/dL | 10.4–34.7 nmol/L | Morning, fasting; guidelines use ~300 ng/dL as the diagnostic threshold, confirmed twice |
| Free testosterone | 5–21 pg/mL | 17–73 pmol/L | Method-dependent; calculated values differ from direct assays |
| Estradiol (E2) | 10–40 pg/mL | 37–147 pmol/L | Use a sensitive (LC-MS/MS) assay in men; standard immunoassays are unreliable at male concentrations |
| SHBG | 10–57 nmol/L | 10–57 nmol/L | Low in obesity and insulin resistance; high with age, hyperthyroidism, liver disease |
| LH | 1.7–8.6 IU/L | 1.7–8.6 IU/L | Suppressed on exogenous testosterone — expected, not an error |
| FSH | 1.5–12.4 IU/L | 1.5–12.4 IU/L | Suppressed on exogenous testosterone |
| Hematocrit | 40–52 % | 0.40–0.52 | Guidelines advise investigating and modifying therapy above roughly 54 % |
| Hemoglobin | 13.5–17.5 g/dL | 135–175 g/L | Rises with testosterone therapy |
| PSA | Age-dependent; commonly < 4 ng/mL | < 4 µg/L | Baseline before therapy and monitored after, per urology guidance |
Worked conversions
- Total testosterone 420 ng/dL → 420 × 0.0347 = 14.6 nmol/L.
- Total testosterone 12 nmol/L → 12 × 28.8 = 346 ng/dL.
- Estradiol 28 pg/mL → 28 × 3.671 = 103 pmol/L.
- Free testosterone 9 pg/mL → 9 × 3.47 = 31 pmol/L.
- Hemoglobin 16.2 g/dL → 162 g/L.
Reading a panel without over-reading it
- One result is a snapshot. Guidelines require two morning measurements before diagnosing deficiency.
- A number inside the reference interval is not automatically 'optimal', and a number just outside it is not automatically a problem — symptoms and trend matter.
- Assay method changes the number. A switch from immunoassay to mass spectrometry can move estradiol noticeably with no biological change.
- On testosterone therapy, LH and FSH are expected to be suppressed; that finding is the therapy working, not a new diagnosis.
- Hematocrit is the routine safety marker on therapy, alongside PSA and symptom review.
What to track between blood draws
Lab values are interpreted against what you were doing when the sample was taken: the dose, the injection schedule, the time of day, whether it was a trough or mid-cycle draw, and which supplements were on board. Bringing that timeline to an appointment turns a single number into a trend a clinician can act on.
Frequently asked questions
- How do I convert testosterone from ng/dL to nmol/L?
- Multiply nanograms per deciliter by 0.0347. A total testosterone of 500 ng/dL is 17.4 nmol/L. To go the other way, multiply nmol/L by 28.8. US labs usually report ng/dL; UK, European and Australian labs usually report nmol/L, which is why the same result looks wildly different depending on where it was drawn.
- What is a normal testosterone level?
- The Endocrine Society and the American Urological Association both use roughly 300 ng/dL (about 10.4 nmol/L) as the lower threshold for diagnosing testosterone deficiency in adult men, measured on a morning sample and confirmed on a second occasion. Individual laboratory ranges differ because they are derived from that laboratory's own reference population and assay.
- How do I convert estradiol from pg/mL to pmol/L?
- Multiply picograms per milliliter by 3.671. An estradiol of 30 pg/mL is about 110 pmol/L. Conversion in the other direction is pmol/L multiplied by 0.272.
- Why do two labs give me different reference ranges for the same result?
- Reference ranges are assay-specific and population-specific. Immunoassay and mass spectrometry methods do not produce identical numbers, particularly at low concentrations and for estradiol in men. Comparing a value to the range printed on that same report is more meaningful than comparing it to a range you found online.
- Does the time of day matter for a testosterone test?
- Yes. Testosterone follows a daily rhythm and is highest in the morning, so guidelines call for a fasting morning draw, generally before 10am, and a second confirmatory sample before any diagnosis. An afternoon result can read substantially lower in the same person on the same day.
- What is free testosterone and when is it measured?
- Free testosterone is the fraction not bound to SHBG or albumin. It is most useful when SHBG is abnormal — obesity, insulin resistance, thyroid disease, liver disease and some medications shift it — because total testosterone can then misrepresent what tissue actually sees. Calculated free testosterone from total testosterone, SHBG and albumin is the commonly used approach.
References & evidence
Sources cited on this page. Last reviewed September 2026. Corrections: editorial policy.
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018. https://pubmed.ncbi.nlm.nih.gov/29562364/
- American Urological Association. Testosterone Deficiency Guideline. https://www.auanet.org/guidelines-and-quality/guidelines/testosterone-deficiency-guideline
- Centers for Disease Control and Prevention. Hormone Standardization Program (HoSt) — testosterone and estradiol measurement. https://www.cdc.gov/labstandards/hs.html
- National Institute for Health and Care Excellence. Testosterone deficiency — clinical knowledge summary. https://cks.nice.org.uk/topics/testosterone-deficiency/
- Vesper HW, Botelho JC. Standardization of testosterone measurements in humans. J Steroid Biochem Mol Biol. 2010. https://pubmed.ncbi.nlm.nih.gov/20470886/
Cite this page
Clinicians, coaches and writers are welcome to reproduce these conversion factors with attribution to DoseRoutine and a link to https://doseroutine.com/trt-lab-reference-ranges.
Start free in DoseRoutineEducational reference only, not medical advice. Talk to a qualified clinician before starting, stopping or combining any peptide, supplement or medication.