Vitamin D ng/mL to nmol/L Calculator and Conversion Chart
Conversion formula: multiply ng/mL by 2.496 to obtain nmol/L. Divide nmol/L by 2.496 to convert in the opposite direction. The factor is commonly rounded to 2.5.
This is a neutral numerical scale, not a diagnostic interpretation. Use the reference range printed on the laboratory report.
If you have received a vitamin D blood test result from another country, a private testing company or an online laboratory, you may find that its units look unfamiliar. Some laboratories report vitamin D in nanograms per millilitre (ng/mL), while others use nanomoles per litre (nmol/L).
The calculator above converts a 25-hydroxyvitamin D result between these two units. Enter a value into either box and the equivalent result will appear automatically.
Quick conversion
To convert vitamin D from ng/mL to nmol/L, multiply by approximately 2.5. To convert from nmol/L to ng/mL, divide by approximately 2.5.
Vitamin D ng/mL to nmol/L formula
The more precise conversion factor commonly used for 25-hydroxyvitamin D3 is 2.496:
nmol/L = ng/mL multiplied by 2.496
ng/mL = nmol/L divided by 2.496
For quick mental arithmetic, the factor is normally rounded to 2.5. This produces a result that is sufficiently close for ordinary unit comparison, although the calculator uses the more precise 2.496 factor.
Common vitamin D conversions
| Vitamin D in ng/mL | Vitamin D in nmol/L |
|---|---|
| 5 ng/mL | 12.5 nmol/L |
| 10 ng/mL | 25.0 nmol/L |
| 15 ng/mL | 37.4 nmol/L |
| 20 ng/mL | 49.9 nmol/L |
| 25 ng/mL | 62.4 nmol/L |
| 30 ng/mL | 74.9 nmol/L |
| 40 ng/mL | 99.8 nmol/L |
| 50 ng/mL | 124.8 nmol/L |
| 60 ng/mL | 149.8 nmol/L |
| 80 ng/mL | 199.7 nmol/L |
| 100 ng/mL | 249.6 nmol/L |
How do you convert 30 ng/mL to nmol/L?
Multiply 30 by 2.496:
30 multiplied by 2.496 = 74.88 nmol/L
Rounded to one decimal place, 30 ng/mL is approximately 74.9 nmol/L. Using the simpler factor of 2.5 gives 75 nmol/L.
How do you convert 50 nmol/L to ng/mL?
Divide 50 by 2.496:
50 divided by 2.496 = 20.03 ng/mL
Therefore, 50 nmol/L is approximately 20 ng/mL.
Why are vitamin D results reported in different units?
Nanograms per millilitre describe the mass of the measured substance within a volume of blood. Nanomoles per litre describe the number of molecules within a volume.
The United States commonly uses ng/mL for vitamin D results. UK and other international laboratories are more likely to use nmol/L. Neither unit is inherently a different test result. They are two ways of expressing the same concentration when the correct conversion factor is used.
The conversion depends on the molecular weight of the substance being measured. That is why the factor used for vitamin D should not automatically be applied to another vitamin, hormone or laboratory measurement.
Which vitamin D blood test does this calculator convert?
This calculator is intended for 25-hydroxyvitamin D, commonly written as:
- 25(OH)D
- 25-OH vitamin D
- 25-hydroxy vitamin D
- Total vitamin D
- Vitamin D total
25(OH)D is the blood measurement normally used when assessing a person’s vitamin D status.
Do not confuse 25(OH)D with 1,25-dihydroxyvitamin D
A result described as 1,25-dihydroxyvitamin D is a different laboratory test. It may also be written as 1,25(OH)2D, calcitriol or active vitamin D.
That test is frequently reported in pg/mL or pmol/L and uses a different conversion factor. Do not enter a 1,25-dihydroxyvitamin D result into this calculator.
If you are unsure which test appears on your report, look at the full test name and units or ask the laboratory or healthcare professional who requested it.
Does the calculator tell me whether my vitamin D is low?
No. The calculator converts units only. It does not diagnose vitamin D deficiency, recommend supplements or decide whether treatment is needed.
Reference ranges and clinical decision points can differ between laboratories, organisations and patient groups. The meaning of a result can also depend on why the test was requested and whether a person is already taking prescribed vitamin D.
Use the reference range printed beside the result on your own laboratory report. Speak to a GP, pharmacist or another qualified healthcare professional if the result is outside that range or you are uncertain about its meaning.
Can I use the result to choose a vitamin D dose?
A converted blood result should not be used by itself to select a high-dose vitamin D supplement. The calculator changes the unit, not the clinical meaning of the result.
Treatment doses for confirmed deficiency may differ from ordinary supplements. They may also depend on medical history, other medicines, calcium levels and the reason for testing.
If a clinician has prescribed vitamin D, follow that plan rather than changing the dose because of an online conversion.
Why the precise result may differ slightly
You may see 30 ng/mL shown as 75 nmol/L on one website and 74.9 nmol/L on another. This is usually a rounding difference.
- Using 2.5 gives exactly 75 nmol/L.
- Using 2.496 gives 74.88 nmol/L.
Both calculations describe approximately the same converted concentration. This calculator displays a sensible number of decimal places rather than suggesting that an online conversion is more precise than the original laboratory measurement.
Frequently asked questions
What is 10 ng/mL of vitamin D in nmol/L?
Ten ng/mL is approximately 25 nmol/L.
What is 20 ng/mL in nmol/L?
Twenty ng/mL is approximately 49.9 nmol/L, normally rounded to 50 nmol/L.
What is 30 ng/mL in nmol/L?
Thirty ng/mL is approximately 74.9 nmol/L, commonly rounded to 75 nmol/L.
What is 40 ng/mL in nmol/L?
Forty ng/mL is approximately 99.8 nmol/L, commonly rounded to 100 nmol/L.
What is 50 ng/mL in nmol/L?
Fifty ng/mL is approximately 124.8 nmol/L, commonly rounded to 125 nmol/L.
What is 50 nmol/L in ng/mL?
Fifty nmol/L is approximately 20 ng/mL.
What is 75 nmol/L in ng/mL?
Seventy-five nmol/L is approximately 30 ng/mL.
What is 100 nmol/L in ng/mL?
One hundred nmol/L is approximately 40.1 ng/mL.
Can I enter a decimal value?
Yes. The calculator accepts whole numbers and decimal values. It also accepts either a decimal point or decimal comma.
Does the calculator store my blood test result?
No. The calculation runs inside your web browser. The value is not submitted through a form or saved by the calculator.
Final takeaway
To convert a 25(OH)D vitamin D result from ng/mL to nmol/L, multiply it by approximately 2.5. To convert from nmol/L to ng/mL, divide by approximately 2.5.
The calculator performs the arithmetic instantly in either direction. Remember that it is a unit-conversion tool, not a diagnostic test. Always interpret the converted number using the reference range on the original laboratory report.
Sources and further reading
- NIH Office of Dietary Supplements: Vitamin D measurement and unit conversion
- AMA Manual of Style: Laboratory unit converter
- Standardisation of 25-hydroxyvitamin D measurements
Important: This calculator provides a mathematical unit conversion for general information. It does not diagnose vitamin D deficiency, interpret a blood test or recommend a supplement dose. Use the reference range supplied by the laboratory and discuss concerns with a qualified healthcare professional.
