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UK labs report vitamin D in nmol/L; US sources use ng/mL. Divide nmol/L by 2.496 to get ng/mL, or multiply ng/mL by 2.496 to go the other way. Convert any value below, or read it off the table.
1 ng/mL = 2.496 nmol/L, so 1 nmol/L = 0.4006 ng/mL.
One ng/mL is 2.496 nmol/L. To go from nmol/L to ng/mL, divide by 2.496. To go the other way, multiply by the same number. So 50 nmol/L is 20 ng/mL, and 30 ng/mL is 75 nmol/L. The tables below cover the values most reports print.
| nmol/L | ng/mL |
|---|---|
| 15 | 6.0 |
| 20 | 8.0 |
| 25 | 10.0 |
| 30 | 12.0 |
| 35 | 14.0 |
| 40 | 16.0 |
| 45 | 18.0 |
| 50 | 20.0 |
| 55 | 22.0 |
| 60 | 24.0 |
| 70 | 28.0 |
| 75 | 30.0 |
| 80 | 32.1 |
| 90 | 36.1 |
| 100 | 40.1 |
| 110 | 44.1 |
| 125 | 50.1 |
| 150 | 60.1 |
| 175 | 70.1 |
| ng/mL | nmol/L |
|---|---|
| 5 | 12.5 |
| 10 | 25.0 |
| 12 | 30.0 |
| 15 | 37.4 |
| 20 | 49.9 |
| 25 | 62.4 |
| 30 | 74.9 |
| 35 | 87.4 |
| 40 | 99.8 |
| 45 | 112.3 |
| 50 | 124.8 |
| 60 | 149.8 |
| 70 | 174.7 |
| 80 | 199.7 |
| 100 | 249.6 |
Values are rounded. The converter above takes any figure, decimals included. Converting the unit does not tell you whether the level is adequate, so once you have the number in the unit you want, our guide to the vitamin D blood test in the UK explains what the reference range on your report is doing, and vitamin D deficiency covers the symptoms people usually arrive with.
Most people convert a vitamin D result because a US chart and a UK report disagree. They are not measuring different things. They draw the lines in different places, in different units. Here are the UK bands, written out both ways.
| Status | nmol/L | ng/mL | What it suggests |
|---|---|---|---|
| Deficient | Below 25 | Below 10 | The UK threshold for deficiency |
| Insufficient | 25 to 50 | 10 to 20 | Below where most clinicians want you |
| Adequate | 50 to 75 | 20 to 30 | A sensible target for most adults |
| Ample | Above 75 | Above 30 | Comfortable stores, no need to push higher |
The 25 nmol/L line is the UK's own. It comes from the Scientific Advisory Committee on Nutrition, the group that sets the country's nutrient recommendations.
“In order to protect musculoskeletal health, it is recommended that the serum 25(OH)D concentration of all individuals in the UK should not fall below 25 nmol/L at any time of the year.”
— Scientific Advisory Committee on Nutrition, Vitamin D and Health, 2016
Note what that sentence is and is not. SACN calls 25 nmol/L a population protective level: the figure everyone should stay above, year round. It is not a diagnosis line. Writing about rickets, the same report says plainly that a serum concentration of 25 nmol/L “is not a clinical threshold diagnostic of the disease”. A single number below it does not name a condition, and a number above it does not rule one out.
This is where the units catch people out. Say your report reads 55 nmol/L. Convert it and you get about 22 ng/mL. Plenty of US charts call 22 ng/mL insufficient, so the number looks alarming. UK guidance puts the same result comfortably above the protective level. Nothing changed except which country wrote the chart.
Two habits save a lot of worry. Convert first, then read the result against a range in the matching unit. And read your own lab's printed range before any chart, because that is the one your result was reported against. Our guide to the vitamin D blood test goes through a full report line by line.
How this is worked out
Uses the standard conversion factor for 25-hydroxyvitamin D: 1 ng/mL = 2.496 nmol/L (molar mass 400.6 g/mol), so 1 nmol/L = 0.4006 ng/mL.
This tool is for general wellbeing information and is not a diagnosis or medical advice. It places the numbers you enter in context; it cannot tell you whether you have a condition. If a result concerns you, or you have symptoms, speak to your GP.
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