25-OH vitamin D nmol/L → ng/mL
Convert 25-hydroxyvitamin D from nmol/L to ng/mL
Sources last checked: 2026-10-13
25-OH vitamin D nmol/L → ng/mL
Convert 25-hydroxyvitamin D from nmol/L to ng/mL
Applies to 25-hydroxyvitamin D (the status marker), not to 1,25-dihydroxyvitamin D, which is reported in pmol/L or pg/mL.
What is the 25-OH vitamin D nmol/L → ng/mL?
25-hydroxyvitamin D, the circulating marker of vitamin D status, is reported in nmol/L in most European labs and in ng/mL in Germany (often), Turkey and the USA. The AMA Manual of Style SI table gives 2.496 nmol/L per ng/mL, from the molar mass of 25-hydroxyvitamin D₃ (400.6 g/mol).
When to use it
- Comparing vitamin D results with thresholds expressed in the other unit
- Reading guidelines that use ng/mL (US) or nmol/L (Europe)
- Explaining results to patients
When not to use it
- 1,25-dihydroxyvitamin D (calcitriol), measured in pmol/L or pg/mL
- Vitamin D supplement doses (IU or µg) — different quantity
How it is calculated
25-OH-D (ng/mL) = 25-OH-D (nmol/L) ÷ 2.496 (≈ ÷ 2.5)
Clinical pearls and limitations
- Applies to 25-hydroxyvitamin D (the status marker), not to 1,25-dihydroxyvitamin D, which is reported in pmol/L or pg/mL.
- Quick check: nmol/L ÷ 2.5 ≈ ng/mL (50 nmol/L ≈ 20 ng/mL; 75 ≈ 30).
- Assays differ by up to 10–20 %; follow-up should use the same lab.
- Supplement dose conversion: 1 µg = 40 IU.
Frequently asked questions
How do I convert vitamin D from nmol/L to ng/mL?
Divide by 2.496 (≈ 2.5). Example: 50 nmol/L ≈ 20 ng/mL.
What is 30 ng/mL vitamin D in nmol/L?
About 75 nmol/L.
Is the conversion the same for vitamin D2 and D3?
Labs report total 25-OH-D with the D₃-based factor; the small molar mass difference of D₂ is ignored in practice.
Evidence and guidelines
Have a follow-up question?
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