Vitamin D Converter
Enter your 25-hydroxyvitamin D result in the unit your lab used. US labs report ng/mL; labs in the UK, Canada, Australia and most of Europe report nmol/L, so the same level reads 30 on one report and 75 on another.
Educational tool, not a diagnosis. It converts 25-hydroxyvitamin D, the test that measures your vitamin D status. It does not apply to 1,25-dihydroxyvitamin D (reported in pg/mL or pmol/L), which is a different test, or to supplement doses in IU. Cut-offs differ between guidelines; read your result against the range printed on your own report and discuss any supplementation plan with your clinician.
The conversion, in one line
To go from ng/mL to nmol/L, multiply by 2.496. To go from nmol/L to ng/mL, divide by 2.496. That factor is not an estimate: nanomoles count molecules and nanograms weigh them, and one mole of 25-hydroxyvitamin D weighs about 400.6 grams, so the two units are locked together. Dividing by 2.5 is a fine shortcut in your head, it is off by less than a fifth of a percent.
That is the opposite of the situation with Lp(a), where no exact conversion exists because the particle itself varies in size from person to person. If you landed here from a cholesterol report, the Lp(a) converter explains why that one has to return a range.
ng/mL to nmol/L: the reference table
The values most people arrive with. The right-hand column uses the same cut-points as the converter above: the Institute of Medicine (IOM) bands as summarised by the NIH Office of Dietary Supplements, the UK deficiency line, and the 30 ng/mL “sufficient” threshold from the Endocrine Society's 2011 guideline.
| Vitamin D in ng/mL | Same level in nmol/L | Where that sits |
|---|---|---|
| 10 ng/mL | 25 nmol/L | Deficient (UK deficiency line) |
| 12 ng/mL | 30 nmol/L | Deficiency threshold (IOM) |
| 15 ng/mL | 37 nmol/L | Inadequate for some people |
| 20 ng/mL | 50 nmol/L | Adequate (IOM) |
| 25 ng/mL | 62 nmol/L | Adequate (IOM) |
| 30 ng/mL | 75 nmol/L | Sufficient (old Endocrine Society line) |
| 40 ng/mL | 100 nmol/L | Sufficient |
| 50 ng/mL | 125 nmol/L | Upper end of the IOM range |
| 60 ng/mL | 150 nmol/L | Above 50 ng/mL |
| 80 ng/mL | 200 nmol/L | Above 50 ng/mL |
| 100 ng/mL | 250 nmol/L | Top of most lab ranges |
| 150 ng/mL | 374 nmol/L | Toxicity reported above this |
nmol/L to ng/mL: the same table in reverse
If your lab is in the UK, Canada, Australia or most of Europe, your report is in nmol/L, while most articles and supplement advice written in the US quote ng/mL. This is the direction you need to read one against the other.
| Vitamin D in nmol/L | Same level in ng/mL | Where that sits |
|---|---|---|
| 25 nmol/L | 10.0 ng/mL | Deficient (UK deficiency line) |
| 30 nmol/L | 12.0 ng/mL | Deficiency threshold (IOM) |
| 40 nmol/L | 16.0 ng/mL | Inadequate for some people |
| 50 nmol/L | 20.0 ng/mL | Adequate (IOM) |
| 60 nmol/L | 24.0 ng/mL | Adequate (IOM) |
| 75 nmol/L | 30.0 ng/mL | Sufficient (old Endocrine Society line) |
| 100 nmol/L | 40.1 ng/mL | Sufficient |
| 125 nmol/L | 50.1 ng/mL | Upper end of the IOM range |
| 150 nmol/L | 60.1 ng/mL | Above 50 ng/mL |
| 200 nmol/L | 80.1 ng/mL | Above 50 ng/mL |
| 250 nmol/L | 100.2 ng/mL | Top of most lab ranges |
Why the cut-offs disagree
The unit is the easy part. The harder part is that the people who set the thresholds do not agree on them. The IOM, which set the US dietary reference intakes in 2011, considers 20 ng/mL (50 nmol/L) enough for bone health in nearly everyone. The Endocrine Society's 2011 guideline called below 20 ng/mL (50 nmol/L) “deficient”, 21 to 29 ng/mL “insufficient” and 30 ng/mL (75 nmol/L) and above “sufficient”, and many US lab reports still print that 30 to 100 ng/mL range. In 2024 the Society published a new guideline that no longer endorses a specific sufficiency level and advises against routine vitamin D testing in healthy adults under 75. The UK uses a lower deficiency line again, 25 nmol/L.
So a result of 25 ng/mL (62 nmol/L) is “adequate” by one definition and “insufficient” by another, without anyone being wrong about the arithmetic. What 30 means in practice, and what the trials say about going higher, is covered in vitamin D at 30 ng/mL; a lower result is covered in vitamin D at 20 ng/mL, and the wider picture in vitamin D deficiency.
Three conversions that trip people up
Blood level versus dose. IU measures how much vitamin D is in a supplement, not how much is in your blood. 1 microgram of vitamin D3 is 40 IU, so 25 micrograms is 1,000 IU, but there is no formula from the IU you take to the ng/mL you end up with: the same dose raises levels differently with body weight and starting level.
The wrong vitamin D test. 25-hydroxyvitamin D is the test that measures your status, and it is what this converter handles. 1,25-dihydroxyvitamin D is the active hormone, present in a thousand times smaller amounts, reported in pg/mL or pmol/L, and it can be normal or even high while you are deficient. Its own factor is different (1 pg/mL is about 2.4 pmol/L).
µg/L and ng/mL. Some reports write µg/L. It is the same quantity as ng/mL, so 30 µg/L is 30 ng/mL and 75 nmol/L. No conversion needed.
If you are comparing vitamin D with other markers on the same panel, the factors for testosterone, glucose, triglycerides, cholesterol, insulin and creatinine are listed in the table at the bottom of the Lp(a) converter.
Frequently asked questions
- How do you convert vitamin D from ng/mL to nmol/L?
- Multiply by 2.496. A 25-hydroxyvitamin D level of 30 ng/mL is 74.9 nmol/L, usually rounded to 75. The factor is exact because it comes from the weight of the vitamin D molecule, so unlike some other blood tests there is no approximation involved.
- How do you convert vitamin D from nmol/L to ng/mL?
- Divide by 2.496, or multiply by 0.4006. A level of 75 nmol/L is 30 ng/mL, 50 nmol/L is 20 ng/mL and 125 nmol/L is 50 ng/mL. If you only need a quick estimate, dividing by 2.5 gets you within a fraction of a unit.
- Is 75 nmol/L the same as 30 ng/mL?
- Yes. 75 nmol/L and 30 ng/mL are the same vitamin D level written in two unit systems. US labs report ng/mL, while labs in the UK, Canada, Australia and most of Europe report nmol/L, which is why the same person can see 30 on one report and 75 on another.
- What is a normal vitamin D level in nmol/L?
- By the Institute of Medicine definition, 50 nmol/L (20 ng/mL) and above is adequate for bone health in nearly everyone, and below 30 nmol/L (12 ng/mL) is associated with deficiency. Levels above 125 nmol/L (50 ng/mL) have been linked to potential adverse effects. UK guidance uses 25 nmol/L as its deficiency threshold. Always read your result against the range on your own report.
- Can I convert my vitamin D blood level to IU?
- No. IU (international units) measures a dose of vitamin D in a supplement or food, not the concentration in your blood. 1 microgram of vitamin D3 is 40 IU, but there is no fixed link between the IU you take and the ng/mL or nmol/L you end up with: the response varies with body weight, starting level and absorption.
- Does this converter work for 1,25-dihydroxyvitamin D?
- No. This tool converts 25-hydroxyvitamin D, the standard test for vitamin D status. 1,25-dihydroxyvitamin D is the active hormone, measured in much smaller amounts in pg/mL or pmol/L, and it is not used to judge whether you have enough vitamin D.
- Does Merios store these numbers?
- No. The converter runs entirely in your browser. Your inputs never leave your device and are not sent to a server.
Track this in Merios
One vitamin D curve, whatever unit each lab used.
Merios reads the units off each report you upload and keeps every marker on one scale, so a result in nmol/L from one lab and one in ng/mL from another sit on the same line instead of looking like two different people.
References: Ross AC, Manson JE, Abrams SA, et al. The 2011 report on dietary reference intakes for calcium and vitamin D from the Institute of Medicine: what clinicians need to know. J Clin Endocrinol Metab 2011;96(1):53-58. · Holick MF, Binkley NC, Bischoff-Ferrari HA, et al. Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2011;96(7):1911-1930. · Demay MB, Pittas AG, Bikle DD, et al. Vitamin D for the prevention of disease: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2024;109(8):1907-1947. · NIH Office of Dietary Supplements, Vitamin D: Fact Sheet for Health Professionals. · Scientific Advisory Committee on Nutrition, Vitamin D and Health, 2016. · Educational tool, not a diagnosis; interpret any result with the reference range printed on your own report and with your physician.