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Vitamin D (25-OH) — nmol/L to ng/mL
Converts vitamin D from nmol/L to ng/mL, the factor taken from its molar mass. One nmol/L is 0.400638 ng/mL.
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In short
To convert vitamin D from nmol/L to ng/mL, multiply by 0.400638 — so one nmol/L is 0.400638 ng/mL, and one ng/mL is 2.49602 nmol/L. 20 ng/mL is 50 nmol/L; 30 ng/mL is 75 nmol/L; 50 ng/mL is 125 nmol/L. The factor comes from the molar mass, because 25-hydroxyvitamin D has a molar mass of 400.64 g/mol; that is why it differs for every analyte and why a single "lab unit converter" factor does not exist. The factor is almost exactly 2.5, which makes this one of the few lab conversions that can be done reliably in your head — and one where the two systems produce numbers so different that guidance quoted in one is routinely misread as the other. The widely cited figures of 20 and 30 in ng/mL are 50 and 75 in nmol/L. This converts units. It does not interpret results, does not compare your value against a reference interval, and is not a substitute for the clinician who ordered the test — reference intervals differ between laboratories, methods and populations.
How to use the Vitamin D (25-OH) — nmol/L to ng/mL
- Type the value you want to convert.
- Pick the unit you are converting from and the unit you want.
- The converted value and the exact conversion factor are shown instantly.
About the Vitamin D (25-OH) — nmol/L to ng/mL
The factor is almost exactly 2.5, which makes this one of the few lab conversions that can be done reliably in your head — and one where the two systems produce numbers so different that guidance quoted in one is routinely misread as the other. The widely cited figures of 20 and 30 in ng/mL are 50 and 75 in nmol/L.
What people use it for
- Reading a vitamin D result issued in nmol/L when you are used to ng/mL.
- Comparing an old report with a new one after moving country or changing laboratory.
- Following a study or a guideline written in the other unit system.
Details
| This conversion | 1 nmol/L = 0.400638 ng/mL |
|---|---|
| Conventional unit | ng/mL — ng/mL in the US; nmol/L in the UK, Europe, Canada and Australia. |
| Factor | 1 ng/mL = 2.49602 nmol/L (divide by 0.400638 to go back) |
| Where it comes from | Molar mass: 25-hydroxyvitamin D has a molar mass of 400.64 g/mol |
| Worked examples | 20 ng/mL is 50 nmol/L; 30 ng/mL is 75 nmol/L; 50 ng/mL is 125 nmol/L |
| Privacy | The arithmetic runs in your browser. Nothing you type is sent anywhere or stored. |
The factor is printed on the page so the arithmetic can be checked rather than trusted. This converts units. It does not interpret results, does not compare your value against a reference interval, and is not a substitute for the clinician who ordered the test — reference intervals differ between laboratories, methods and populations.
Where this tool stops
This converts units. It does not interpret results, does not compare your value against a reference interval, and is not a substitute for the clinician who ordered the test — reference intervals differ between laboratories, methods and populations.
Frequently asked questions
Is a vitamin D of 30 good or bad?
That depends entirely on which unit it is in — 30 ng/mL and 30 nmol/L are very different amounts, since one is two and a half times the other. This tool tells you which is which; what the value means for you is a question for a clinician, and the thresholds themselves differ between national guidelines.
What is the exact factor?
One nmol/L is 0.400638 ng/mL, and the reverse is 2.49602. It is derived rather than looked up: 25-hydroxyvitamin D has a molar mass of 400.64 g/mol, and the conversion follows from that.
Does this tool tell me if my result is normal?
No. It converts a number between two units and stops there, on purpose. Reference intervals differ between laboratories and methods, and a single value means little without the rest of your results and the person who ordered them.
Do I need an account to use the Vitamin D (25-OH) — nmol/L to ng/mL?
No charge and no sign-up. There is no free tier to run out of because there is no paid tier — inputtesthub.com is funded by advertising rather than by metering the tool.
Is the Vitamin D (25-OH) — nmol/L to ng/mL safe to use with private information?
No. The Vitamin D (25-OH) — nmol/L to ng/mL runs entirely in your browser using JavaScript. Because the work happens locally, the tool also keeps working if your connection drops, and closing the tab is all it takes to discard everything.
What do people use the Vitamin D (25-OH) — nmol/L to ng/mL for most?
In practice it gets used for three things: reading a vitamin D result issued in nmol/L when you are used to ng/mL. Comparing an old report with a new one after moving country or changing laboratory. Following a study or a guideline written in the other unit system. It is built for exactly those cases rather than being a general-purpose tool with this bolted on.
When is the Vitamin D (25-OH) — nmol/L to ng/mL not the right tool?
This converts units. It does not interpret results, does not compare your value against a reference interval, and is not a substitute for the clinician who ordered the test — reference intervals differ between laboratories, methods and populations. Knowing where a tool stops being trustworthy matters more than the cases where it works.
Which values should I know?
This conversion is 1 nmol/L = 0.400638 ng/mL. Conventional unit is ng/mL — ng/mL in the US; nmol/L in the UK, Europe, Canada and Australia.. Factor is 1 ng/mL = 2.49602 nmol/L (divide by 0.400638 to go back). These are printed on the page itself, so you do not have to take them on trust.
How precise is the result?
The calculation runs in double precision and the result is shown to ten significant figures, so converting a value and converting it back returns the original. What is displayed is rounded for readability; what is copied is not.
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