MedeliX
Start asking

Vitamin D (25-OH) ng/mL → nmol/L

Convert vitamin d (25-oh) from ng/mL to nmol/L

Sources last checked: 2026-11-03

Vitamin D (25-OH) ng/mL → nmol/L

Convert vitamin d (25-oh) from ng/mL to nmol/L

Fill in every field to see the result.

Converts units only; reference ranges depend on the laboratory, the assay and the patient.

Source: AMA Manual of Style, 11th ed. (Oxford Academic) — Units of measure converter, Table 2: Selected laboratory tests and conversion factors.Open

What is the Vitamin D (25-OH) ng/mL → nmol/L?

Serum 25-hydroxyvitamin D (25-OH-D), the usual marker of vitamin D status, is reported in ng/mL in the USA, Turkey and by many labs in Germany and Austria, and in nmol/L in the UK and many other European countries. This converter multiplies by 2.496, the AMA Manual of Style factor, which corresponds to the molar mass of 25-hydroxyvitamin D3 (400.6 g/mol).

When to use it

  • Comparing a ng/mL result with studies or guidelines that use nmol/L
  • Following a patient whose results come from labs using different units
  • Reading European and UK literature on vitamin D status

When not to use it

  • 1,25-dihydroxyvitamin D (calcitriol): a different molecule, reported in pg/mL or pmol/L with its own factor
  • Vitamin D doses in IU or µg — those describe intake, not serum concentration
  • Deciding on deficiency or supplementation: cut-offs differ between guidelines and laboratories

How it is calculated

25-OH vitamin D (nmol/L) = 25-OH vitamin D (ng/mL) × 2.496

Clinical pearls and limitations

  • Converts units only; reference ranges depend on the laboratory, the assay and the patient.
  • Check that the report says 25-OH-D (calcidiol), not 1,25-(OH)2-D; mixing them up is a frequent error.
  • The factor is based on 25-OH-D3. 25-OH-D2 is slightly heavier, but most assays report total 25-OH-D and use the same factor.
  • Immunoassays and LC-MS/MS can give noticeably different results; compare serial values from the same method where possible.
  • A quick estimate: nmol/L is about two and a half times the ng/mL value.

Frequently asked questions

How do I convert vitamin D from ng/mL to nmol/L?

Multiply by 2.496. For example, 20 ng/mL × 2.496 = 49.9, about 50 nmol/L.

What is 30 ng/mL vitamin D in nmol/L?

30 × 2.496 = 74.88, about 75 nmol/L.

Is ng/mL the same as µg/L for vitamin D?

Yes. 1 ng/mL equals 1 µg/L, so the same factor (2.496) converts both to nmol/L.

Evidence and guidelines

  1. Primary source: AMA Manual of Style, 11th ed. (Oxford Academic) — Units of measure converter, Table 2: Selected laboratory tests and conversion factors.
  2. PubChem compound summary: 25-hydroxyvitamin D3 (calcifediol) (CID 5283731), molecular weight 400.6 g/mol.

Have a follow-up question?

Medelix answers clinical questions from current guidelines and studies — every statement with its source.

Related calculators

Embed this calculatorFree to use on your website, intranet or teaching page. Copy the code below.
<iframe src="https://medelix.ai/en/embed/vitamin-d-ngml-to-nmol" title="Vitamin D (25-OH) ng/mL → nmol/L – Medelix" width="100%" height="620" style="border:0;max-width:720px" loading="lazy"></iframe> <p><a href="https://medelix.ai/en/calculators/vitamin-d-ng-ml-to-nmol-l">Vitamin D (25-OH) ng/mL → nmol/L calculator by Medelix</a></p>

For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.