How to Convert Testosterone Lab Results Between ng/dL and nmol/L

Converting testosterone units can be confusing – but it’s also essential. In this post, we demystify ng/dL vs nmol/L and show you exactly how to convert testosterone lab values between these units, so you can confidently interpret your TRT bloodwork and testosterone levels anywhere.

Managing your testosterone replacement therapy (TRT) often means dealing with lab reports. One common frustration? Labs around the world use different units for testosterone. In the United States, results typically come in ng/dL, while many other countries report nmol/L. If you’ve ever scratched your head comparing a study or forum post in nmol/L to your own labs in ng/dL (or vice versa), you’re not alone. These unit differences make testosterone lab value conversion a key skill for any informed patient. In fact, it’s challenges like these that helped inspire the creation of TRT Monitor (as described in our post Why I Built TRT Monitor). The good news is that converting testosterone units is straightforward once you know the basics.

ng/dL vs nmol/L: What’s the Difference?

ng/dL (nanograms per deciliter) and nmol/L (nanomoles per liter) are two ways to measure the concentration of testosterone in your blood. They ultimately represent the same thing (the amount of testosterone in a given volume of blood) but use different measurement systems:

ng/dL – “Nanograms per deciliter” is a conventional unit. A nanogram is a billionth of a gram, and a deciliter is one-tenth of a liter (about 100 milliliters). This unit is commonly used in the United States and a few other countries for lab reports.
nmol/L – “Nanomoles per liter” is an International System (SI) unit. A nanomole refers to an amount of substance (in this case, testosterone molecules) rather than mass. It’s the unit favored in most of the world (UK, Canada, Europe, etc.) for reporting hormone levels.

So why the two units? It largely comes down to regional conventions and historical practices in medicine. Neither unit is “better” – they are just different ways of expressing the concentration. However, converting between them isn’t as simple as moving a decimal point, because one measures mass and the other counts molecules. The conversion requires a specific factor derived from testosterone’s molecular weight.

When each is used:
If you’re in a country like the US, your testosterone levels on labs will likely be in ng/dL.
If you live in or get labs from Europe or Canada, you’ll see nmol/L.
Understanding both is important if you’re consuming international research or discussing results in global forums. For example, a UK doctor might say “normal total testosterone is ~10–30 nmol/L,” whereas a US doctor might say “300–1000 ng/dL” – they’re referring to the same range, just in different units.

Conversion Formulas and Examples (ng/dL ↔ nmol/L)

Converting testosterone units is actually easy once you know the magic number. Testosterone’s conversion factor is 0.03467. This lets us switch between ng/dL and nmol/L quickly:

To convert ng/dL to nmol/L: multiply by 0.03467.
(In other words, ng/dL × 0.03467 = nmol/L.)
To convert nmol/L to ng/dL: multiply by 28.84.
(In other words, nmol/L × 28.84 = ng/dL.)

You don’t need to memorise the exact number – using 0.0347 and 28.8 will get you very close in practice.

Sample Testosterone Values (Converted)

Here are a few reference points to help make sense of typical values:

300 ng/dL ≈ 10.4 nmol/L
(Often considered the low end of the “normal” range in U.S. guidelines.)
500 ng/dL ≈ 17.3 nmol/L
(A mid-range level for adult men.)
1000 ng/dL ≈ 34.7 nmol/L
(Upper end of “high normal.”)

Conversely, if a research paper lists testosterone as:

15 nmol/L ≈ 433 ng/dL
25 nmol/L ≈ 721 ng/dL

Having this conversion skill ensures you’re always comparing apples to apples, no matter which unit you come across.

Tip: Use a Tool to Convert Testosterone Units Instantly

Rather than crunching numbers on paper or worrying about rounding errors, you can let a tool do the work for you. We built TRT Monitor’s free TRT Unit Converter specifically to make unit conversions effortless. Just enter your testosterone value in one unit, select the conversion direction, and it will immediately display the result in the other unit – no math required.

Our converter isn’t limited to total testosterone, either. It supports various hormones and lab values, ensuring you get accurate results for TRT bloodwork conversions of all kinds. It’s mobile-friendly and quick to use, so you can pull it up during doctor visits or while reading medical literature. This free tool is just one of the ways TRT Monitor aims to simplify tracking your therapy (check out our other features designed for TRT patients).

Using an automated converter saves time and avoids mistakes. For instance, if you mistype a number on a calculator, you might think 20 nmol/L equals 520 ng/dL when it should be ~577 ng/dL. The online tool eliminates that risk and gives you confidence that you’re interpreting your testosterone levels correctly, whether you’re converting ng/dL to nmol/L or the other way around.

Final Thoughts

Understanding how to convert testosterone units is more than a trivial math exercise – it’s about taking charge of your health information. When you know that 1 ng/dL ≈ 0.0347 nmol/L, you can seamlessly translate your results to any format. This is especially important when consulting different doctors, reading research from abroad, or discussing your testosterone levels with others online. A number only makes sense in context, and now you can always put your results in the right context.

To get the most from your TRT, remember that tracking is key. Logging your blood test results in a consistent unit (and converting when necessary) allows you to spot trends over time and have informed discussions with your healthcare provider. Don’t let unit confusion stand in the way of managing your treatment. With a little knowledge and the right tools, you can ensure your TRT bloodwork makes sense at a glance.

Ready to stay on top of your TRT journey?
Consider using a dedicated app like TRT Monitor to log all your labs, track your symptoms, and get clear visual trends. It’s built to handle details like unit differences so you don’t have to.