Lab units · vitamin D
Vitamin D converter, ng/mL to nmol/L.
Convert a 25-hydroxyvitamin D (25-OH D) blood level between ng/mL, used in the US, and nmol/L, used in Canada, the UK, Australia and Europe.
Convert a vitamin D level
Result
Enter a 25-OH vitamin D value in either box.
How the conversion works
The blood test measures 25-hydroxyvitamin D. With a molar mass of about 400.6 g/mol (25-hydroxyvitamin D3; D2 is 412.7), 1 ng/mL = 1 µg/L = 2.496 nmol/L. So nmol/L = ng/mL × 2.496, often rounded to 2.5, and ng/mL = nmol/L ÷ 2.496.
Worked example
30 ng/mL = 30 × 2.496 = 75 nmol/L. 50 nmol/L = 50 ÷ 2.496 = 20.0 ng/mL.
Vitamin D conversion chart
| ng/mL | nmol/L |
|---|---|
| 10 ng/mL | 25 nmol/L |
| 12 ng/mL | 30 nmol/L |
| 20 ng/mL | 50 nmol/L |
| 25 ng/mL | 62 nmol/L |
| 30 ng/mL | 75 nmol/L |
| 40 ng/mL | 100 nmol/L |
| 50 ng/mL | 125 nmol/L |
| 60 ng/mL | 150 nmol/L |
| 80 ng/mL | 200 nmol/L |
| 100 ng/mL | 250 nmol/L |
About cut-offs
Different bodies use different cut-offs for sufficiency, and laboratories report their own ranges. This page deliberately shows none, because a conversion should not be read as a judgement. For context, the NIH Office of Dietary Supplements explains the units and the ranges used in different guidance: Vitamin D fact sheet for health professionals. Do not start, stop or change a supplement based on a unit conversion.
Sources
NIH ODS fact sheet above (states 1 nmol/L = 0.4 ng/mL, i.e. 1 ng/mL = 2.5 nmol/L) and molar mass from NIH PubChem (calcifediol).
Frequently asked questions
How do I convert vitamin D from ng/mL to nmol/L?
Multiply by 2.496 (about 2.5). For example 20 ng/mL is about 50 nmol/L.
How do I convert nmol/L to ng/mL?
Divide by 2.496, or multiply by 0.4. For example 75 nmol/L is 30 ng/mL.
Which vitamin D test does this apply to?
The 25-hydroxyvitamin D blood test, the one most commonly ordered. It is not valid for 1,25-dihydroxyvitamin D, which has a different molar mass.
Is my level too low?
This page cannot say. Cut-offs differ between guidance and laboratories. Ask the clinician who ordered the test.
Reference information, not medical advice
This page converts units only. It does not interpret a result, and units and reference intervals differ between laboratories. Ask the clinician who ordered the test or the reporting laboratory what a result means for you. If you are worried about a result or symptoms, contact a health professional; in an emergency call your local emergency number.