Last updated: June 2026 · Reviewed June 2026 · Built by the InjectBuddy team
How do you convert testosterone units? ng/dL and nmol/L
To convert a testosterone result from ng/dL to nmol/L, multiply by 0.0347; to go from nmol/L to ng/dL, divide by 0.0347 (the same as multiplying by 28.84). That single factor of 0.0347 comes from testosterone's molar mass of about 288.4 g/mol, and it lets a US lab number and a UK or Australian lab number describe the very same blood draw.
Key takeaways
- ng/dL → nmol/L: multiply by 0.0347.
- nmol/L → ng/dL: divide by 0.0347 (or multiply by 28.84).
- ng/mL → ng/dL: multiply by 100 (a deciliter is 100 mL).
- Free T pg/mL → pmol/L: multiply by 34.7; pg/mL → ng/dL divide by 10.
Put your numbers into the free testosterone index calculator to check a conversion alongside your total T, SHBG, and albumin in one place.
How this is calculated
Mass-per-volume units (ng/dL, ng/mL, pg/mL) count nanograms or picograms of testosterone in a fixed volume of serum. Molar units (nmol/L, pmol/L) count molecules instead. Because one mole of testosterone weighs about 288.4 grams, converting between mass and moles always runs through that molar mass — this is standard SI conversion, confirmed by the testosterone physiology and measurement literature (Nassar & Leslie, StatPearls 2026).
Starting from ng/dL: 1 ng/dL is 0.01 ng/mL, which is 10 pg/mL, which is 0.00001 mg/L. Divide that mass concentration by the molar mass and scale into nanomoles per liter and the whole chain collapses to a single multiply-by-0.0347 step. The reverse simply divides. Nothing here depends on the patient, the assay brand, or the reference range — it is pure arithmetic, so the only way to get it wrong is to use the wrong factor or misread the units printed on the report.
Conversion factors and common values
| From | To | Do this | Example |
|---|---|---|---|
| ng/dL | nmol/L | x 0.0347 | 600 → 20.8 |
| nmol/L | ng/dL | x 28.84 | 15 → 433 |
| ng/mL | ng/dL | x 100 | 6.0 → 600 |
| ng/dL | ng/mL | ÷ 100 | 900 → 9.0 |
| pg/mL (free) | ng/dL | ÷ 10 | 120 → 12.0 |
| pg/mL (free) | pmol/L | x 34.7 | 120 → 4164 |
The first two rows are exact inverses of each other; rounding 1 ÷ 0.0347 gives 28.84. The free-testosterone rows use the same molar mass scaled down by a thousand, because free T is reported in the much smaller pg/mL or pmol/L range. The conceptual difference between these units — why a US clinic prints 600 and a UK clinic prints 20.8 for the same man — is covered in testosterone units explained: nmol/L vs ng/dL.
Worked conversions
Each block below is a single conversion you can reproduce with a phone calculator. Round to one decimal for nmol/L and to a whole number for ng/dL unless your lab reports finer.
A US report reads 600 ng/dL. Multiply by 0.0347: 600 x 0.0347 = 20.82 nmol/L. This is a typical mid-range total testosterone.
A borderline-low result of 280 ng/dL: 280 x 0.0347 = 9.72 nmol/L, just under the commonly quoted ~10 nmol/L lower threshold.
A UK report of 15 nmol/L: divide by 0.0347, so 15 ÷ 0.0347 = 432 ng/dL (or 15 x 28.84 = 433, the rounding gap).
A high-normal 28 nmol/L: 28 x 28.84 = 807 ng/dL. Useful when a US-based prescriber wants the number in their own units.
Some labs print total T as 6.5 ng/mL. A deciliter holds 100 mL, so multiply by 100: 6.5 x 100 = 650 ng/dL = 22.6 nmol/L.
Free testosterone of 110 pg/mL: divide by 10 to reach ng/dL, so 110 ÷ 10 = 11.0 ng/dL of free T.
The same 110 pg/mL free T in SI units: 110 x 34.7 = 3817 pmol/L. Free T uses the same molar mass as total, scaled to picomoles.
Convert 900 ng/dL to nmol/L: 900 x 0.0347 = 31.23. Convert back: 31.23 x 28.84 = 900.7 ng/dL — the tiny drift is rounding, confirming the factors are inverses.
Free testosterone is a different unit again
Total testosterone and free testosterone are reported in different scales because free T is only 1–3% of the total. A calculated free T from total T, SHBG, and albumin — the Vermeulen method — is the most widely used estimate (Vermeulen, Verdonck & Kaufman, 1999), and it returns free T in pg/mL, ng/dL, or pmol/L depending on the lab. Always confirm which unit a free-T figure is in before converting, then use the free testosterone index calculator rather than eyeballing it. The interpretation of those numbers is covered in free testosterone explained and the calculation walkthrough in the free testosterone calculator guide.
Common conversion mistakes
The biggest error is mixing the total-T factor (0.0347) with the free-T pg/mL scale — they share the molar mass but not the magnitude. The second is confusing ng/mL with ng/dL, a 100-fold gap that turns a healthy 6 ng/mL into a wrongly alarming "6 ng/dL". A third is comparing your nmol/L number against a US reference range printed in ng/dL; convert first, then compare, because reference ranges are diagnostic context, not interchangeable units. None of this conversion changes whether a level is normal — that judgement belongs to a clinician reading the result against the right range (Bhasin et al., Endocrine Society 2018).
So, how do you convert testosterone units?
To convert testosterone from ng/dL to nmol/L, multiply by 0.0347; to go the other way, divide by 0.0347 (the same as multiplying by 28.84). That single factor comes from testosterone’s molar mass of about 288.4 g/mol and lets a US result and a UK or Australian result describe the same blood draw. Convert any value instantly with the free testosterone calculator.
FAQ
How do I convert ng/dL to nmol/L?
Where does the 0.0347 factor come from?
Is ng/mL the same as ng/dL?
Why is free testosterone in pg/mL instead of ng/dL?
Is 0.0347 the right factor for free testosterone too?
Sources
- 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.
- Nassar GN, Leslie SW. Physiology, Testosterone. StatPearls. 2026. NCBI Bookshelf NBK526128.
- Leslie SW, Soon-Sutton TL, Khan MAB. Male Hypogonadism (reference ranges in ng/dL). StatPearls. NCBI Bookshelf NBK532933.
- Bhasin S, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018. PubMed PMID: 29562364.
- CDC. Safe Injection Practices to Prevent Transmission of Infections to Patients. CDC injection safety guidance.
This guide is a units and arithmetic reference, not medical advice. Converting a number does not interpret it — always check your result against the correct reference range with your prescriber or lab.