Hormone health
Testosterone Unit Converter
Got a total testosterone result in one unit and a reference range in another? Enter your number in ng/dL, nmol/L, or ng/mL and see the other two instantly, using the exact molar-mass math. It's a simple converter — not an interpretation or a diagnosis — and everything is worked out on your own device.
This is a unit converter, not an interpretation — converting doesn't change what a level means, and whether a result is low or normal is for your lab's range and a clinician, not this tool.
Testosterone unit converter
Converted with the molar mass of testosterone (288.42 g/mol). This is a math utility, not a measured result or a diagnosis — reference ranges vary by lab and assay, and interpreting a level belongs with the free-testosterone calculator and the clinician who ordered your labs.
How it works
The conversion, in plain terms
US labs usually report testosterone in ng/dL; most of the world and the SI system use nmol/L; some reports use ng/mL. They all describe the same amount — only the notation differs, which is why a result can look very different from a reference range printed in another unit.
Two of the units — ng/dL and ng/mL — measure mass per volume, so converting between them is a clean factor of 100 (a deciliter is 100 millilitres). Converting to nmol/L counts molecules instead of mass, so it uses testosterone's molar mass of 288.42 g/mol (formula C19H28O2): one nanomole weighs 288.42 nanograms.
1 nmol/L = 288.42 ng/L = 28.842 ng/dL = 0.28842 ng/mL (commonly rounded to 28.85 and 0.2885)
1 ng/mL = 100 ng/dL (1 dL = 100 mL)
So: ng/dL ÷ 28.842 = nmol/L · nmol/L × 28.842 = ng/dL · ng/dL ÷ 100 = ng/mL · ng/mL × 100 = ng/dL. This tool derives every factor from the exact 288.42 g/mol molar mass.
Worked example
A total testosterone of 500 ng/dL is the same result as 17.34 nmol/L (500 ÷ 28.842) and 5 ng/mL (500 ÷ 100). Nothing physiological changed — those three numbers are one level written three ways.
Reference context
A general orientation — not a diagnostic threshold
Reference ranges vary by lab, assay, age, and population, so always compare against the range printed on your own report. The figures below are one widely-cited harmonized total-testosterone range for healthy men aged 19–39, shown in all three units only to help you read a converted number.
| Unit | Harmonized range (men 19–39) | Where it's used |
|---|---|---|
| ng/dL | ~264–916 | United States |
| nmol/L | ~9.2–31.8 | SI / most countries |
| ng/mL | ~2.64–9.16 | Some labs / older reports |
Some labs and guidelines use a lower cut-off near 300 ng/dL (~10.4 nmol/L, ~3 ng/mL) when evaluating possible low testosterone. A value near or outside these bands isn't automatically abnormal — only your report's range and your clinician can interpret it. To go further, the free-testosterone calculator estimates the usable fraction, and the ADAM symptom screen checks whether symptoms fit.
Next steps
Related checks and tools
Free-T calculator (Vermeulen)
Once your units line up, estimate free and bioavailable testosterone — and see why free-T can read low when total-T looks normal.
Low testosterone (ADAM)
The validated symptom screen for low T — check whether what you're feeling fits the pattern worth a blood test.
Semen analysis interpreter
Read a semen-analysis report against the WHO reference values in plain English.
Find testing & care
Clinics, at-home kits, and free options if a change in your sexual health makes you want to get checked.
Sources
Where this comes from
The conversions are exact and derive from the molar mass of testosterone (C19H28O2 = 288.42 g/mol, PubChem CID 6013): 1 nmol/L = 28.842 ng/dL = 0.28842 ng/mL, and 1 ng/mL = 100 ng/dL by unit definition. The reference-range context and the framing of what a result means follow the Endocrine Society and American Urological Association testosterone guidelines and Cleveland Clinic patient information. This page converts units and shows a general reference context; interpreting a level belongs with the free-testosterone calculator and the clinician who ordered your labs.
Medically Reviewed & Fact-Checked · Updated
Reviewed by EasySTD Editorial Team
Compiled and checked by EasySTD's editorial team against CDC and public-health sources. This is educational information, not a substitute for advice from a licensed clinician. Our editorial guidelines →
4 Sources
Data & references
- PubChem: Testosterone (Compound CID 6013) — molecular formula C19H28O2, molar mass 288.42 g/molhttps://pubchem.ncbi.nlm.nih.gov/compound/Testosterone
- Endocrine Society: Testosterone Therapy for Hypogonadism (clinical practice guideline)https://www.endocrine.org/clinical-practice-guidelines/testosterone-therapy
- American Urological Association: Evaluation and Management of Testosterone Deficiency (guideline)https://www.auanet.org/guidelines-and-quality/guidelines/testosterone-deficiency-guideline
- Cleveland Clinic: Low Testosterone (Male Hypogonadism)https://my.clevelandclinic.org/health/diseases/15603-low-testosterone-male-hypogonadism
EasySTD is an information and comparison directory, not a healthcare provider. This tool is a general-purpose math utility: it converts units and does not produce a diagnosis, a measured result, or medical advice, and it does not create a doctor-patient relationship. Testosterone results are interpreted by a clinician using your lab's reference range, the assay, your age, and your symptoms. Never start or stop any treatment based on this tool — discuss your results with a licensed clinician.
Good to Know
Testosterone unit conversion: frequently asked questions
How to convert between ng/dL, nmol/L, and ng/mL, why labs use different units, where the 28.85 factor comes from, what's a normal level in each unit, and how private this is.
How do I convert testosterone between ng/dL, nmol/L, and ng/mL?
It's just multiplication. Because ng/dL and ng/mL both measure mass per volume, 1 ng/mL always equals 100 ng/dL (a deciliter is 100 millilitres), so you multiply ng/mL by 100 to get ng/dL, or divide ng/dL by 100 to get ng/mL. Converting to or from nmol/L is where the molecule matters: nmol/L counts molecules rather than mass, so you use testosterone's molar mass of 288.42 g/mol. One nmol/L works out to 28.842 ng/dL (often rounded to 28.85), so multiply nmol/L by about 28.84 to get ng/dL, or divide ng/dL by about 28.84 to get nmol/L. This tool does all of that for you and shows all three at once — the underlying value is the same, only the notation changes.
Why do labs report testosterone in different units?
It comes down to convention. Laboratories in the United States usually report testosterone in ng/dL (nanograms per deciliter), while most of the rest of the world and the SI system use nmol/L (nanomoles per liter). Some labs and older reports use ng/mL (nanograms per milliliter), which is simply ng/dL divided by 100. The differences are purely about how the same amount is written down, not about the testosterone itself — a level of 500 ng/dL, 17.34 nmol/L, and 5 ng/mL are all the identical result. Converting matters most when your result is printed in one unit but the reference range you're comparing against, or an article you're reading, uses another.
Where does the 28.85 (or 28.84) conversion factor come from?
From chemistry. A mole of any substance weighs its molar mass in grams, and testosterone (chemical formula C19H28O2, PubChem CID 6013) has a molar mass of about 288.42 g/mol. So one nanomole of testosterone weighs 288.42 nanograms. Spread that nanomole through one liter and you have 288.42 ng/L, which is 28.842 ng/dL (there are 10 deciliters in a liter) or 0.28842 ng/mL. That 28.842 is frequently rounded to 28.85 in textbooks and lab handouts; both describe the same relationship. This converter uses the value derived straight from the 288.42 g/mol molar mass so the math stays exact.
What is a normal total testosterone level in each unit?
There is no single universal number, because reference ranges depend on the lab, the assay, your age, and the population — always compare against the range printed on your own report. For orientation only, one widely-cited harmonized reference range for healthy men aged 19 to 39 is roughly 264 to 916 ng/dL, which is about 9.2 to 31.8 nmol/L, or about 2.6 to 9.2 ng/mL. Some labs and guidelines use a lower cut-off near 300 ng/dL (about 10.4 nmol/L, or 3 ng/mL) when evaluating possible low testosterone. These are general context to help you read a result — not a diagnostic line — and a value near or outside them is interpreted by a clinician, not by this tool.
Does converting the units change what my result means?
No. Converting is purely cosmetic arithmetic: 500 ng/dL and 17.34 nmol/L are the exact same amount of testosterone, so nothing about your physiology or your result changes when you switch units. What can trip people up is comparing a result in one unit against a reference range in another — that mismatch, not the conversion, is what makes a number look alarmingly high or low. This converter only changes the notation. Whether a level is low, normal, or high — and what to do about it — depends on your lab's range and your symptoms, so use the free-testosterone calculator and a clinician for interpretation.
Is what I enter private?
Yes. This converter runs entirely in your browser. The number you enter is converted on your own device and is never sent to a server, saved, or shared — close the tab and it's gone. It's a general-purpose math utility for education; it isn't medical advice, a diagnosis, or a test result, and it can't replace the clinician who ordered your labs.
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