Testosterone unit converter
Convert total testosterone between ng/dL and nmol/L — and see where the number sits against the standard reference range and the typical TRT target.
Reference ranges vary between labs and assays — always read your result against the range printed on your own report. Informational only, not medical advice. Medical disclaimer.
Why labs report different units
US labs report testosterone in ng/dL — nanograms per decilitre, a measure of mass. Labs in the UK, Europe and Australia report nmol/L — nanomoles per litre, a measure of how many molecules are present.
Same hormone, same blood, two ways of counting it: one weighs it, the other counts it. Neither is more accurate. It only becomes a problem when you switch labs, move country, or compare numbers with someone who tests somewhere else — which is most conversations about TRT.
The conversion
Testosterone has a molar mass of 288.4 g/mol. That fixes the relationship between the two units at a single constant:
ng/dL = nmol/L ÷ 0.0347
Some sources multiply by 28.8 for the reverse direction. It's the same number — 1 ÷ 0.0347 — but dividing by one constant keeps a value identical when you convert it back and forth.
Quick reference
Common total testosterone values, both directions.
| ng/dL | nmol/L |
|---|---|
| 100 | 3.5 |
| 200 | 6.9 |
| 300 | 10.4 |
| 400 | 13.9 |
| 500 | 17.4 |
| 600 | 20.8 |
| 700 | 24.3 |
| 800 | 27.8 |
| 900 | 31.2 |
| 1000 | 34.7 |
| 1100 | 38.2 |
| 1200 | 41.6 |
| nmol/L | ng/dL |
|---|---|
| 5 | 144 |
| 10 | 288 |
| 15 | 432 |
| 20 | 576 |
| 25 | 720 |
| 30 | 865 |
| 35 | 1009 |
| 40 | 1153 |
Common questions
What's the conversion factor for testosterone?+
Multiply ng/dL by 0.0347 to get nmol/L. Divide nmol/L by 0.0347 to get ng/dL. The factor comes from testosterone's molar mass of 288.4 g/mol, so it's fixed — it doesn't vary by lab or assay.
Does this work for free testosterone?+
No — and this is where most converters get it wrong. Free testosterone is reported in pg/mL, ng/dL, pmol/L or nmol/L depending on whether the lab measured it directly or calculated it, and those differ by orders of magnitude. There's no single safe factor. Convert free T only against the specific units and method printed on your own report.
What's a typical total testosterone range?+
Most labs print a reference range around 300–1000 ng/dL (10.4–34.7 nmol/L) for adult men, though the exact numbers vary by lab, assay and age band. Men on TRT commonly aim for the upper half of that range or slightly above. Your own lab's printed range is the one that applies to your result.
Why does my UK result look so much smaller than a US one?+
Because nmol/L numbers are roughly 29× smaller than the same result in ng/dL. A UK reading of 25 nmol/L and a US reading of 720 ng/dL are the same testosterone level. Nothing is wrong with either result.
Which unit should I track in?+
Whichever one your lab uses, so you're not converting every time. The friction appears when your results come from more than one lab, or from more than one country — that's the case Andrometrics is built for: it reads whichever unit your PDF used and lets you switch the display with a tap.
One number is a snapshot.
Andrometrics reads your blood test PDFs and charts every marker over time — in whichever unit you prefer.
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