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

If you've ever tried comparing your testosterone results to a study or forum post and the numbers looked completely different, there's a good chance the units were different. Here's how to convert between ng/dL and nmol/L so you always know where you stand.

When you're on TRT, you end up reading a lot of lab reports. One thing that trips people up is that labs around the world use different units for testosterone. In the US, results come in ng/dL. Most other countries - the UK, Canada, Europe, Australia - use nmol/L. So when someone on a forum says their levels are "25" and yours say "700", you might not be comparing the same thing at all. This is one of those small annoyances that inspired TRT Monitor in the first place (more on that in Why I Built TRT Monitor). The conversion itself is pretty simple once you know the formula.

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

ng/dL (nanograms per deciliter) and nmol/L (nanomoles per liter) both measure the concentration of testosterone in your blood. Same thing, 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. This is what US labs use.
nmol/L - "Nanomoles per liter" is an SI (International System) unit. Instead of measuring mass, it counts molecules. Most of the world uses this one.

Why two units? Mostly just regional convention and historical medical practice. Neither is better. But converting between them isn't as simple as moving a decimal point - one measures mass and the other counts molecules, so you need a specific conversion factor based on testosterone's molecular weight.

Where you'll see each one: US labs will almost always give you ng/dL. UK, European, Canadian, and Australian labs will give you nmol/L. This matters when you're reading international research or talking to people in different countries. A UK doctor saying "normal total testosterone is ~10-30 nmol/L" and a US doctor saying "300-1000 ng/dL" are talking about the same range.

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

The conversion is straightforward. Testosterone's conversion factor is 0.03467:

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

You don't need to memorise the exact number - using 0.0347 and 28.8 will get you close enough.

Sample Testosterone Values (Converted)

Some reference points to give you a feel for typical values:

300 ng/dL ≈ 10.4 nmol/L (Often considered the low end of "normal" in US 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.")

Going the other way:

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

Once you have this down, you can always compare like-for-like no matter which unit you come across.

Tip: Use a Tool to Convert Testosterone Units Instantly

If you don't want to do the maths yourself, we built a free TRT Unit Converter for exactly this. Plug in your value, pick the direction, and you get the answer straight away.

It's not limited to total testosterone either - it handles various hormones and lab values you'd encounter in TRT bloodwork. It works on mobile too, so you can pull it up at an appointment or while reading a study. It's one of several features we built to make tracking TRT less of a hassle.

Using a converter also avoids mistakes. If you fat-finger a number on a calculator, you might think 20 nmol/L equals 520 ng/dL when it's actually ~577 ng/dL. The online tool removes that risk.

Final Thoughts

Knowing how to convert testosterone units is a small thing, but it saves you a lot of confusion. When you know that 1 ng/dL ≈ 0.0347 nmol/L, you can translate your results to any format - useful when you're seeing different doctors, reading international research, or comparing notes with others online.

Tracking your blood test results in a consistent unit (and converting when needed) helps you spot trends over time and have better conversations with your doctor. Don't let unit confusion get in the way of understanding your own numbers.